<PAGE>   1


                         PAYMENT DEFERRAL AGREEMENT            EXHIBIT 10.17


         This Agreement dated March 26, 1999 is between Stanwich Financial
Services Corp. ("SFSC") and NAB Asset Corporation ("NAB").

                                    RECITALS:

         1.       NAB is indebted to SFSC under the following instruments
                  (collectively, the "NOTES" and, individually, a "NOTE"):

                  (1)      Promissory Note dated June 27, 1997 in the original
                           principal amount of $800,000;

                  (2)      Line of Credit Note dated August 28, 1997 in a
                           principal amount not to exceed $5,000,000;

                  (3)      Promissory Note dated September 30 , 1997 in the
                           original principal amount of $2,500,000;

                  (4)      Promissory Note dated December 30, 1997 in the
                           original principal amount of $4,000,000 (acquired by
                           SFSC by assignment from Consumer Portfolio Services,
                           Inc.);

                  (5)      Promissory Note dated March 12, 1998 in the original
                           principal amount of $900,000; and

                  (6)      Promissory Note dated March 13, 1998 in the original
                           principal amount of $1,100,000.

         2.       NAB has requested that SFSC agree to amend the Notes to defer
                  principal and interest payments thereunder, and SFSC is
                  willing to do so on the terms and conditions hereinafter set
                  forth.

        NOW THEREFORE, the parties agree as follows:

         1.       Subject to paragraphs 2, 3, 4 and 5, below, each of the Notes
                  is hereby amended to grant to NAB the option to defer making
                  any or all Scheduled Payments until January 3, 2000. As used
                  herein, the term "Scheduled Payments" means payments of
                  principal and interest under the Notes that are scheduled by
                  the terms thereof to be paid during the period beginning on
                  the date hereof and ending on December 31, 1999.

<PAGE>   2


         2.       Each of the Notes is hereby further amended to provide that,
                  if pursuant to paragraph 1, above, NAB defers any Scheduled
                  Payment that is an interest payment, the amount thereof shall
                  itself bear interest, at a rate equal to the rate at which
                  interest accrues on the principal of such Note, during the
                  period from the original due date of such deferred payment (as
                  scheduled in the applicable Note, before giving effect to this
                  Agreement) to the date such deferred payment is made. Each
                  item of additional interest provided for in this paragraph 2
                  shall be payable on the earlier to occur of (i) January 3,
                  2000 or (ii) the date of which the deferred interest to which
                  such additional interest relates is paid.

         3.       As used herein, the term "Corporate Transaction" means any
                  transaction in which (i) NAB borrows money from a lending
                  institution and/or (ii) all or substantially all of the
                  capital stock or assets of a subsidiary of NAB are sold (in
                  one or more transactions) other than in the ordinary course of
                  business. If, after the date hereof, NAB consummates one or
                  more Corporate Transactions prior to the payment of the Notes
                  in full and if the aggregate net proceeds received therefrom
                  by NAB and/or its subsidiaries at any time or from time to
                  time exceeds $400,000 or such lesser amount as NAB's Board of
                  Directors may determine, then, in such case, NAB shall use the
                  entire amount of such excess net proceeds (up to but not
                  exceeding the aggregate amount of NAB's indebtedness under the
                  Notes, as amended hereby) to pay or prepay its indebtedness
                  under the Notes, not later than the next business day after
                  each such receipt of excess net proceeds by NAB and/or its
                  subsidiaries; provided, however, that NAB shall be obligated
                  to so use such excess net process only to the extent it can do
                  so without causing a breach or default by itself or any such
                  subsidiary under any agreement existing on the date hereof to
                  which it or any such subsidiary is a party. NAB hereby agrees
                  to use its best efforts to effect one or more Corporate
                  Transactions as soon as possible with gross proceeds of at
                  least $5,000,000; provided that such transactions are
                  determined by NAB's Board of Directors to be fair to and in
                  the best interests of NAB and its shareholders. Any failure by
                  NAB to make any prepayment required by this paragraph 3 shall
                  constitute a default or event of default under all of the
                  Notes, with the result that, at SFSC's option, all of the
                  indebtedness under all of the

<PAGE>   3




                  Notes shall accelerate and become immediately due and payable,
                  without demand, notice presentment or any other legal
                  formalities. If the amount prepaid pursuant to this paragraph
                  is less than the aggregate amount then outstanding under the
                  Notes, then, in such case, such prepayment shall be applied,
                  first, towards the payment of interest (including additional
                  interest, if any, under paragraph 2, above) under the Notes
                  and, second, towards the payment of principal under the Notes,
                  in both cases in such order and such manner as may be
                  determined by SFSC in its discretion.

         4.       The foregoing amendments to the Notes shall not be construed
                  to amend, alter, modify, limit, impair or otherwise affect in
                  any manner SFSC's right under any Note to accelerate the
                  payment of the indebtedness thereunder upon the occurrence of
                  a default or event of default thereunder, in accordance with
                  the terms of such Note.

         5.       NAB's rights to prepay the Notes without penalty, as provided
                  for therein, is hereby confirmed.



        IN WITNESS WHEREOF, the parties have signed this Agreement on the date
first above written.


STANWICH FINANCIAL SERVICES CORP.           NAB ASSET CORPORATION


By: /s/ Charles E. Bradley, Jr.             By: /s/ Alan Ferree
    ----------------------------------          --------------------------------
Name: Charles E. Bradley, Jr.               Name: Alan Ferree
Title: Vice - President                     Title: Senior Vice President