Amazon Seller Loses Again

I had a customer return an item. Amazon auto-authorized the return. The original sale was a seller fulfilled item. The customer returned a different, less expensive item. The item they originally purchased was $49.95. The item they returned was a used item that originally cost $26.50. I tried to file a safe-T claim but it was denied because it was a seller fulfilled item. So, it appears I have no way to recover my loses by this theft. Amazon has set up a process for theft by customers where the sellers lose again.