EBay Refused refund for wrong product

I ordered a wrong product; I told the company and I apologized. They offered me a 20% discount if I would keep the product. I told them I had no use for it, and took it to UPS and returned it within the allotted time. I have the receipt and delivery receipt to where I shipped it back. They said they never received it back and they refuse to refund my money; UPS says otherwise. Again, I have receipts to prove it.

$76 might not mean all that much to most people, but it does to me, because I'm on Social Security. The company will not even talk to me; they closed the account; I can't call, or email, or chat with them.