Dear _________________
In reference to your letter of ________________ (date), we have no record of having received the merchandise you returned.
In order to issue you a refund for the ________________ (amount), we request that you provide us with the following information:
1. Date you returned the merchandise
2. Form of shipment (UPS, Post office, etc.)
3. Copies of any correspondence to us in regard to returning merchandise
Your cooperation in this matter will enable us to trace the parcel.
Thank you for your help. I will be looking forward to your letter.