Our document template is designed to make the process of writing an "Inform a Customer of an Overpayment" letter quick, easy, and stress-free. This brief but important letter notifies a customer that he or she has overpaid you.It can serve as a very good customer relations letter. Our service provides various examples of refund letters, including sample overpayment letters, refund request letters, and more. In this article, we'll show you how to write a refund request letter template that not only grabs attention but also persuades companies to act in your favor. This sample letter has choices to help you build your letter. When you write, pick the words that describe your situation. Overpayment Information. If you have received an overpayment notice from DETR, you may be required to repay the excess amount. The salary overpayment resulted because .