Had a buyer purchase an item on 12/6. I shipped it on 12/7 and purchased the postage through Amazon. Unfortunately, USPS picked up the item but did not scan it into their system. I live in MD and the first entry on the tracking was 12/26 at a distribution center in FL. The buyer contacted me on 12/23 and said that because they weren’t going to receive the item in time for Christmas they wanted a full refund and the item. I told them that they could return the item when it arrived for a full refund. The buyer received the item on 12/30 and on 1/1 messaged me and again demanded a full refund. I again told them they could return it for a full refund. Instead they filed an A-Z on 1/1 (2 days after they received the item) and claimed item not received. Amazon granted them the claim. How should I fight this? The tracking clearly shows the item was delivered and I purchased the postage through Amazon but the USPS didn’t update the tracking until after the package was supposed to be delivered.