Customer opened a return and has returned a different item (Serial numbers do not match)

@Spencer_Amazon They have just e-mailed me saying they have upheld he decision for the claim as I appealed with evidence because the customer has returned the item.... and they then quoted the tracking number. Completely ignoring the fact they have returned a different item to what was sold! I'm at a loss with amazons back end team. have provided serial number proof and I had pre warned them quoting the support case BEFORE the A-Z claim was opened. I got a notification saying the buyer did not provide any information and the claim was closed. Only for the claim to be re-opened and awarded in the buyers favour.... this is a joke. They also said I did not refund the buyer within 2 business days. I received the you have refunded the buyer e-mail this morning. I received no notification saying the claim had been re-opened but I definitely received an e-mail saying the case has been closed and you have nothing to do on your end. Even with serial number proof and picture evidence amazon are awarding a blatant scammer and effecting my metrics?! Please sort this out