https://sellercentral.amazon.com/gp/help/external/G1791
> What should I do if a buyer wants to return an item?
> All Amazon sellers are required to accept returns.
https://sellercentral.amazon.com/gp/help/external/G200495860
If it comes back with parts missing, you can do a partial refund. Buyer can still do an A-Z claim, but you’re in a much stronger position, especially if you have proof of how you sent it and how you received it.
They did change to automatically approving returns a few years ago, but with an opt-out ability. My guess is either OP's product fell into an obscure exception to that rule, or OP opted out, or something similar.
Amazon makes the laws and acts as a court now? I don't understand why people respect "company policy" so much. The laws of the land take precedence. We are not corporate slaves.
Also, people respect 'company policy' when they want to do business with that company.
And that's your problem. If you deny a return within the return period, you're in violation of Amazon policy, and the A-Z team will rightly rule against you. The correct response is to accept the return, then deny a refund after it comes back to you because it wasn't sent back with the same accessories you sent it with.