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.Providers have the option to submit a Request For Extended Repayment Schedule (ERS). A complete ERS request should be submitted immediately. The salary overpayment resulted because . If we have identified an overpayment and request a refund, please mail the check along with a copy of the overpayment request letter we sent you.