Exhibit 10.47C

THIRD AMENDMENT TO EMPLOYMENT AGREEMENT

This Third Amendment to Employment Agreement is made and entered into on the
22nd day of February, 2008, among CSG SYSTEMS INTERNATIONAL, INC. (“CSGS”), a
Delaware corporation, CSG SYSTEMS, INC. (“Systems”), a Delaware corporation, and
RANDY R. WIESE (the “Executive”). CSGS and Systems collectively are referred to
in this Third Amendment and the Employment Agreement as the “Companies.”

* * *

WHEREAS, the Companies and the Executive entered into an Employment Agreement
dated April 25, 2006 (the “Employment Agreement”), a First Amendment thereto
dated March 6, 2007 (the “First Amendment”), and a Second Amendment thereto
dated August 14, 2007 (the “Second Amendment”); and

WHEREAS, the Companies and the Executive desire to further amend the Employment
Agreement as herein set forth;

NOW, THEREFORE, in consideration of the foregoing recitals and the agreements of
the parties contained in this document, the Companies and the Executive agree as
follows:

1. Effective as of January 1, 2008, Paragraph 4 of the Employment Agreement
hereby is amended in its entirety so as to read as follows:

“4. Base Salary. For all services to be rendered by the Executive pursuant to
this Agreement, the Companies agree to pay the Executive during the term of this
agreement a base salary (the “Base Salary”) for each calendar year at an annual
rate which is not less than the annual rate of the Executive’s Base Salary in
effect on December 31 of the immediately preceding calendar year. The
Executive’s annual incentive bonus provided for in Paragraph 5 and all other
compensation and benefits to which the executive is or may become entitled
pursuant to this agreement or under any plans or programs of the Companies shall
be in addition to the Base Salary.”

2. Upon the execution of this Third Amendment to Employment Agreement, any
subsequent reference to the Employment Agreement shall mean the Employment
Agreement as amended by the First Amendment, the Second Amendment, and this
Third Amendment to Employment Agreement. As amended by the First Amendment, the
Second Amendment, and this Third Amendment to Employment Agreement, the
Employment Agreement shall remain in full force and effect according to its
terms.

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IN WITNESS WHEREOF, each of the parties has caused this Third Amendment to
Employment Agreement to be executed as of the date first set forth above.

 

CSG SYSTEMS INTERNATIONAL, INC., a

Delaware corporation

By:   /s/ Peter E. Kalan   Peter E. Kalan, President and Chief Executive Officer
CSG SYSTEMS, INC., a Delaware corporation By:   /s/ Peter E. Kalan   Peter E.
Kalan, President and Chief Executive Officer /s/ Randy R. Wiese Randy R. Wiese