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.You have to tell your credit or debit card company about any error you're disputing within 60 days of when the first statement with the charge was sent to you. 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. Many times when a third-party payer mistakenly pays a dental provider, the payer will request a refund of the overpaid amount.