So buyer orders oversized item, cost me $50 to ship.

Does a return request with " Did not Authorize purchase" (Not sure how this is even an option....did I just randomly choose this person & charge their card & ship them an oversized item, when none of this is possible on Amazon)

Buyer sends products back, contacts me via message center saying they sent the wrong product. Product arrived today & it's clearly old, used items that I did not sell.

I did a refund of $0, but Amazon is still charging me $50 for the return shipping. Won't allow an Safe-T-Claim either.