SAMPLE JUDGMENT PROOF LETTER - COLLECTION AGENCY. Forms for use in cases filed to collect money from borrowers who have not made credit card, loan, or certain other types of payments.Information from the Legal Advocacy and Resource Center about your rights if you are in debt. Also a sample letter to send to a collection agency. 1. Enter your address at the top of the letter. The letter must outline your complaint, the harm you suffered, and how you want the problem resolved. This is called a 30 Day Demand Letter. Directions: Fill out this letter with your information.