<PAGE>   1


                                                                  EXHIBIT 10D(3)


                           THIRD AMENDMENT TO AMENDED
                          AND RESTATED CREDIT AGREEMENT

         THIS THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT is dated
as of April 4, 2001 ("this Amendment"), by and among NORSTAN, INC., a Minnesota
corporation (the "Borrower"), the banks which are signatories hereto (each
individually, a "Bank," and collectively, the "Banks"), and U.S. BANK NATIONAL
ASSOCIATION, a national banking association, one of the Banks, as agent for the
Banks (in such capacity, the "Agent").

                                    RECITALS

         A. The Borrower, the Banks and the Agent are parties to an Amended and
Restated Credit Agreement dated as of December 20, 2000, as amended by a First
Amendment to Amended and Restated Credit Agreement dated as of March 19, 2001
(the "First Amendment") and as amended by a Second Amendment to Amended and
Restated Credit Agreement (the "Second Amendment") dated as of March 30, 2001
(as amended, the "Credit Agreement").

         B. The Borrower has advised the Banks that (i) it will be unable to
make the principal payments due upon Term Loan A and Term Loan B of the Credit
Agreement due on April 4, 2001, (ii) it has violated certain financial covenants
contained in the Credit Agreement and (iii) it expects to be in violation of
certain financial covenants contained in the Credit Agreement for the month
ended March 31, 2001 and for future reporting periods.

         C. The Borrower has requested that the Banks agree to extend the due
dates for the payments due under Term Loan A and Term Loan B under the Credit
Agreement on the terms set forth in this Agreement, to waive the Borrower's
events of default due to the Borrower's failure to meet its financial covenants
and to modify the Borrower's financial covenants on the terms set forth in this
Amendment.

         NOW, THEREFORE, in consideration of the premises and for other good and
valuable consideration the receipt and adequacy of which are hereby
acknowledged, the parties hereto hereby agree as follows:

         Section 1. Definitions. Capitalized terms used herein and not otherwise
defined herein, but which are defined in the Credit Agreement, shall have the
meanings ascribed to such terms in the Credit Agreement unless the context
otherwise requires.

         Section 2. Amendments to Credit Agreement. Subject to Section 5 hereof,
the Credit Agreement is hereby amended as follows:

                  (a) Amended Definitions. Sections 2.5(b) and 2.5(c) of the
         Credit Agreement are deleted in their entireties and the following is
         substituted in lieu thereof:

                           (b) Term A Loan. The Term A Loan shall be payable as
                  follows (i) one installment of principal in the amount of
                  $500,000 shall be due and payable on April 16, 2001, (ii) two
                  installments of principal in the amount of $1,000,000 each
                  shall be due and payable on May 15, 2001 and





<PAGE>   2


                  June 15, 2001 and (iii) an installment equal to the unpaid
                  balance of Term Loan A, and all accrued and unpaid interest
                  thereon, shall be due and payable on June 29, 2001;

                           (c) Term B Loan. The unpaid balance of the Term B
                  Loan, and all accrued and unpaid interest thereon, shall be
                  due and payable on June 29, 2001;

                  (b) Mandatory Prepayments. The second sentence of Section
         2.6(c) of the Credit Agreement is deleted in its entirety and the
         following is substituted in lieu thereof:

                  Any such prepayments shall be applied, in the following order
                  by the Agent to the Loans ratably to each Bank according to
                  its Revolving Commitment Percentage, Term A Loan Percentage,
                  Term B Loan Percentage or Term C Loan Percentage, as
                  applicable: (i) first, to unpaid principal balance of the Term
                  A Loan, in inverse order of the maturities of the installments
                  thereon (or, in the case of prepayments due to sale or
                  transfers of the type specified in clause (A) of the forgoing
                  sentence, in order of the maturities of the installments
                  thereon), (ii) second, to the unpaid principal balance of the
                  Term B Loan, (iii) third, to the unpaid principal balance of
                  the Term C Loan, (iv) fourth, to the unpaid principal balance
                  of the Revolving Loans (other than the reimbursement
                  obligations with respect to the Existing Letter of Credit) and
                  (v) fifth, to the Holding Account in the amount of the
                  aggregate face amount of the Existing Letter of Credit.

                  (c) Financial Reporting. Sections 5.1(c) and (d) of the Credit
         Agreement are each amended by deleting the clause "45 days" as it
         appears in each such Section and substituting in lieu thereof the
         clause "30 days". Section 5.1(d) of the Credit Agreement is amended by
         deleting the clause "Sections 6.8, 6.16, 6.18 and 6.19" as it appears
         therein and substituting in lieu thereof the clause "Sections 6.8, 6.16
         and 6.18".

                  (d) Ericsson Intercreditor Agreements. The following new
         Section 5.17 is added immediately following Section 5.16 of the Credit
         Agreement:

                           Section 5.17 ERICSSON INTERCREDITOR AGREEMENTS. By
                  April 19, 2001, the Borrower shall furnish to the Agent the
                  Intercreditor Agreements substantially in the form of those
                  attached as Exhibits C and D to the First Amendment hereto,
                  duly executed by the NCI, Ericsson, Inc. or Ericsson Webcom,
                  Inc., as applicable.

                  (e) Amendments to Financial Covenants. Sections 6.15, 6.16,
         6.17, 6.18 and 6.19 of the Credit Agreement are deleted in their
         respective entireties and the following is substituted in lieu thereof:

                           Section 6.15 [RESERVED].

                           Section 6.16 MINIMUM EBITDA. The Borrower will not
                  permit EBITDA, as of the last day of the Borrower's fiscal
                  months ended on or about the



                                      -2-
<PAGE>   3


                  following dates for such fiscal month, to be less than the
                  following indicated amounts:

<TABLE>
<CAPTION>
                  Fiscal Month Ended On or About     Minimum EBITDA
                  ------------------------------     --------------
                  <S>                                <C>
                          March 31, 2001                ($900,000)
                          April 30, 2001               $1,400,000
                          May 31, 2001                   $900,000
                          June 30, 2001                $1,300,000
</TABLE>

                           Section 6.17     [RESERVED].

                           Section 6.18 ADJUSTED LEVERAGE RATIO. The Borrower
                  will not permit the Adjusted Leverage Ratio, as of the last
                  day of the Borrower's fiscal months ended on or about the
                  following dates for such fiscal month, to be greater than the
                  following indicated amounts:

<TABLE>
<CAPTION>
                  Fiscal Month Ended On or About              Maximum Adjusted Leverage Ratio
                  ------------------------------              -------------------------------
                  <S>                                         <C>
                          March 31, 2001                                24.0 to 1.0
                          April 30, 2001                                22.0 to 1.0
                          May 31, 2001                                  24.9 to 1.0
                          June 30, 2001                                 25.0 to 1.0
</TABLE>

                           Section 6.19     [RESERVED].

                  (f) Schedule to Borrower's Pledge Agreement. The Borrower's
         Pledge Agreement is amended by deleting the text following the
         subheading "Part II, Foreign Shares" as it appears therein and
         substituting in lieu thereof the clause "None".

                  (g) Amendment to First Amendment. The First Amendment is
         amended by deleting the text of Sections 5(c) and (d) and substituting
         in lieu of such text the clause "[Reserved]".

                  (h) Amendment of Second Amendment. Section 3(a) of the Second
         Amendment is amended by deleting the clause "($2,179,000), which amount
         is" as it appearing therein. Section 3(b) of the Second Amendment is
         amended by deleting the clause "16.9 to 1.0, which amount is" as it
         appears therein. Section 3(c) of the Second Amendment is amended by
         deleting the clause "(3.2) to 1.0, which amount is" as it appears
         therein.

         Section 3. Waiver of Events of Default. The Borrower has informed the
Banks as follows:

                  (a) that it was not in compliance with its covenant under
         Section 6.16 of the Credit Agreement (as it existed prior to the
         effectiveness of this Amendment) for the period ended February 28,
         2001, in that its actual EBITDA for the fiscal month ended on



                                      -3-
<PAGE>   4


         that date was the less than the minimum EBITDA of $2,195,000 required
         by that Section for that period;

                  (b) that it was not in compliance with its covenant under
         Section 6.18 of the Credit Agreement (as it existed prior to the
         effectiveness of this Amendment) for the fiscal month ended February
         28, 2001, in that the Adjusted Leverage Ratio as of that date was
         greater than the maximum Adjusted Leverage Ratio of 13.7 to 1.0
         required by that Section for that period; and,

                  (c) that it was not in compliance with its covenant under
         Section 6.19 of the Credit Agreement (as it existed prior to the
         effectiveness of this Amendment) for the fiscal month ended February
         28, 2001, in that the Interest Coverage Ratio as of that date was less
         than the minimum Interest Coverage Ratio of 3.9 to 1.0 required by that
         Section for that period;

Each such instance of noncompliance constitutes a Default or Event of Default
under the Credit Agreement (collectively, the "Existing Defaults"). Upon the
satisfaction of the conditions set forth in Section 4 below, each Bank waives
the Existing Defaults. The Banks' agreement to waive the Existing Defaults is
limited to the express terms thereof, and nothing herein shall be deemed a
waiver by the Banks of any other term, condition, representation or covenant
applicable to the Borrower under the Loan Documents (including but not limited
to any future occurrence similar to the Existing Defaults). The waiver by the
Banks set forth herein shall not constitute a waiver by the Banks of any other
Default or Event of Default, if any, under any Loan Document, and shall not be,
and shall not be deemed to be, a course of action with respect thereto upon
which the Borrower may rely in the future, and the Borrower hereby expressly
waives any claim to such effect.

         Section 4. Representations and Warranties of the Borrower. To induce
the Banks and the Agent to execute and deliver this Amendment (which
representations and warranties shall survive the execution and delivery of this
Amendment), the Borrower represents and warrants to the Agent and the Banks
that:

                  (a) this Amendment has been duly authorized, executed and
         delivered by it and this Amendment constitutes the legal, valid and
         binding obligation of the Borrower enforceable against the Borrower in
         accordance with its terms, subject to limitations as to enforceability
         which might result from bankruptcy, insolvency, reorganization,
         moratorium or similar laws or equitable principles relating to or
         limiting creditors' rights generally;

                  (b) the Credit Agreement, as amended by this Amendment,
         constitutes the legal, valid and binding obligation of the Borrower
         enforceable against the Borrower in accordance with its terms, subject
         to limitations as to enforceability which might result from bankruptcy,
         insolvency, reorganization, moratorium or similar laws or equitable
         principles relating to or limiting creditors' rights generally;

                  (c) the execution, delivery and performance by the Borrower of
         the Amendment (i) have been duly authorized by all requisite corporate
         action and, if



                                      -4-
<PAGE>   5


         required, shareholder action, (ii) do not require the consent or
         approval of any governmental or regulatory body or agency, and (iii)
         will not (A) violate (1) any provision of law, statute, rule or
         regulation or its certificate of incorporation or bylaws, (2) any order
         of any court or any rule, regulation or order of any other agency or
         government binding upon it, or (3) any provision of any material
         indenture, agreement or other instrument to which it is a party or by
         which any of its properties or assets are or may be bound, or (B)
         result in a breach of or constitute (alone or with due notice or lapse
         of time or both) a default under any indenture, agreement or other
         instrument referred to in clause (iii)(A)(3) of this Section 4(c);

                  (d) as of the date hereof, no Default or Event of Default has
         occurred which either (a) is continuing or (b) has not been waived by
         the Agent and the Banks as set forth in Section 3 of this Amendment;
         and

                  (e) all the representations and warranties contained in
         Article IV of the Credit Agreement are true and correct in all material
         respects with the same force and effect as if made by the Borrower on
         and as of the date hereof.

         Section 5. Conditions to Effectiveness of this Amendment. This
Amendment shall become effective as of the date first above written when each
and every one of the following conditions shall have been satisfied:

                  (a) The Agent shall have received executed counterparts of
         this Amendment, duly executed by the Borrower and each of the Banks.

                  (b) The Agent shall have received from the Guarantors a
         Consent and Agreement of Guarantors in the form of Exhibit A hereto
         (the "Guarantor Agreements") duly completed and executed by each
         Guarantor.

                  (c) The Agent shall have received a Pledge Agreement executed
         by Norstan International, Inc. covering 65% of its capital stock in
         Norstan UK, Ltd., together with financing statements and stock powers
         in the form prescribed by the Agent, each duly executed by Norstan
         International, Inc.

                  (d) The Agent shall have received such other documents or
         instruments reasonably deemed necessary by the Agent.

         Section 6. Affirmation; Reaffirmation. The Agent, each Bank and the
Borrower each acknowledge and affirm that the Credit Agreement, as hereby
amended, is hereby ratified and confirmed in all respects and all terms,
conditions and provisions of the Credit Agreement, except as amended by this
Amendment, shall remain unmodified and in full force and effect. All references
in any document or instrument to the Credit Agreement are hereby amended and
shall refer to the Credit Agreement as amended by this Amendment. The Borrower
confirms to the Agent and each Bank that the Obligations are and continue to be
secured by the security interest granted by the Borrower in favor of the Agent
under the Borrower's Security Agreement and all of the terms, conditions,
provisions, agreements, requirements, promises, obligations, duties, covenants
and representations of the Borrower under such documents and any and all other




                                      -5-
<PAGE>   6


documents and agreements entered into with respect to the Obligations are
incorporated herein by reference and are hereby ratified and affirmed in all
respects by the Borrower.

         Section 7. General Release. The Borrower hereby releases and discharges
the Agent and each Bank, and each of their officers, directors, employees,
agents and attorneys, from any and all claims, actions and liabilities of any
kind or nature that it or any one claiming through or under the Borrower ever
had or may now have, whether now known or hereafter discovered, arising out of
or in any way relating to: (i) any lending relationship or loan commitment
between the Agent, the Banks and the Borrower prior to the date of this
Amendment; (ii) the Loan Documents; or (iii) the negotiations preceding the
execution and delivery of this Agreement.

         Section 8. General.

                  (a) The Borrower agrees to reimburse the Agent upon demand for
         all reasonable expenses (including reasonable attorneys fees and legal
         expenses) incurred by the Agent in the preparation, negotiation and
         execution of this Amendment and any other document required to be
         furnished herewith, and to pay and save the Agent harmless from all
         liability for any stamp or other taxes which may be payable with
         respect to the execution or delivery of this Amendment, which
         obligations of the Borrower shall survive any termination of the Credit
         Agreement.

                  (b) This Amendment may be executed in as many counterparts as
         may be deemed necessary or convenient, and by the different parties
         hereto on separate counterparts, each of which, when so executed, shall
         be deemed an original but all such counterparts shall constitute but
         one and the same instrument.

                  (c) Any provision of this Amendment which is prohibited or
         unenforceable in any jurisdiction shall, as to such jurisdiction, be
         ineffective to the extent of such prohibition or unenforceability
         without invalidating the remaining portions hereof or affecting the
         validity or enforceability of such provisions in any other
         jurisdiction.

                  (d) This Amendment shall be governed by, and construed in
         accordance with, the internal law, and not the law of conflicts, of the
         State of Minnesota, but giving effect to federal laws applicable to
         national banks.

                  (e) This Amendment shall be binding upon the Borrower, the
         Agent and the Banks and their respective successors and assigns, and
         shall inure to the benefit of the Borrower, the Agent and the Banks and
         the successors and assigns of the Agent and the Banks.


               [Remainder of this page intentionally left blank.]




                                      -6-

<PAGE>   7


         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed as of the day and year first above written.


                                       NORSTAN, INC.


                                       By /s/ Robert J. Vold
                                         ---------------------------------------
                                          Its Treasurer


                                       U.S. BANK NATIONAL ASSOCIATION,
                                       as a Bank and as Agent


                                       By /s/ David C. Larsen
                                         ---------------------------------------
                                          Its VP


                                       HARRIS TRUST AND SAVINGS BANK


                                       By /s/ Lawrence Mizera
                                         ---------------------------------------
                                          Its VP


                                       M&I MARSHALL & ILSLEY BANK


                                       By /s/ Robert A. Nielsen
                                         ---------------------------------------
                                          Its VP


                                       By /s/ Mark R. Hogan
                                         ---------------------------------------
                                          Its SVP


                                       WELLS FARGO BANK MINNESOTA,
                                       NATIONAL ASSOCIATION


                                       By /s/ William J. Kennedy
                                         ---------------------------------------
                                          Its VP




  [Signature Page to Third Amendment to Amended and Restated Credit Agreement]

                                       S-1