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. Refund Letter Format: Requesting someone for the refund of your amount paid? A guide on how to ask for a refund and get your money back, including sample request for refund letters. First, you need to issue a check to your customer using the Accounts Receivable account for the overpayment amount. The Naval Criminal Investigative Service (NCIS) was formally established in January 1993 under the Secretary of the Navy.