Dear [Company Name], I am writing to inform you of a duplicate payment that was made on [date]. After reviewing my financial records, I noticed that I inadvertently made two identical payments for the same invoice [invoice number]. I hereby request a refund of the duplicate payment amount, which was [amount in dollars]. I would appreciate it if you could promptly look into this matter and process the refund accordingly. Furthermore, I have attached the relevant documents for your reference, including copies of both payments and the original invoice. Please let me know if you require any further information or verification. As a valued customer, I trust that [Company Name] will handle this situation promptly and efficiently. I have always appreciated your excellent customer service in the past, and I hope for the same level of professionalism in resolving this issue. I kindly request that the refund be issued in the same form as the original payment [include instructions if necessary, such as bank transfer details, mailing address for a check, etc.]. It would also be helpful to receive a confirmation email once the refund has been processed. If for any reason you require additional information or if there are any complications in processing this refund, please notify me immediately so that we can rectify the situation promptly. Thank you for your attention to this matter, and I look forward to receiving the refund soon. Should you have any questions or concerns, please do not hesitate to contact me at [your contact information]. Yours faithfully, [Your Name] [Your Address] [City, State, ZIP Code] [Email Address] [Phone Number] [Attachments: (list any attached documents e.g., payment receipts, original invoice)]