Amazon Claims Returned Heating Pad Was Never Sent Back

I placed an order on Amazon.com in the US for a heating pad under order number 111-0116507-1734622. I returned this product via a UPS drop‑off point within the 30‑day return period calculated from April 9, but Amazon is now claiming that I did not send the item back. Unfortunately, I no longer have the UPS receipt, but I handed the package over at UPS as instructed in the return process. Because of this situation, I tried to reach Amazon customer service. I managed to get a live chat representative who stated they were in Egypt, but instead of helping, I was repeatedly redirected to the generic customer service page, which is not helpful and does not offer a clear way to reach support. I could not find any working phone number or effective live chat option to actually resolve the issue. My expectation is that Amazon investigates this return, traces the item I handed over to UPS, and updates the status of my order accordingly. I would like Amazon to locate the returned heating pad associated with order 111-0116507-1734622 and correct their records so that I am not held responsible for an item I already sent back.