How can we get the money back while the UPS return label was created by Amazon?

We shipped the item via Amazon Buy Shipping on time.

The customer created the return request before contacting us and dropped off the shipment at a UPS location.

The tracking updates stopped at the end of last year and never moved again.

We filed the claim with UPS the next day after being contacted by the customer. Now the claim has been issued to Amazon since Amazon is the creator of the return shipping label.

The customer submitted the A-to-z claim and we appealed within the time frame submitting all the information we have.

Now the A-to-z team finished investigating but we as the seller never received any credit for the return and the claim was still covered by us the seller.

We need someone from Amazon to look into this issue and offer a fair resolution for us.