Over Payment Refund Letter To Customers Template. Clearly state the decision regarding the refund.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. 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. Refund Letter Format: Requesting someone for the refund of your amount paid? We have identified the following overpayment and are in good faith voluntarily refunding all monies collected in error. First, you need to issue a check to your customer using the Accounts Receivable account for the overpayment amount.