Request for Refund of Duplicate Payment

On [date], you were mailed a check in the amount of $

[dollar amount] per your [date] invoice.
After reviewing your file, we realized that this account

had been paid in full on [date]. Enclosed is a photocopy

of the cancelled check [#] in the amount of $ [dollar

amount].
A reimbursement would be greatly appreciated due to

the duplicate payment. Our apologies for any

inconvenience this error might have caused.
Thank you for your prompt attention to this matter.
Very truly yours,