Refunded for a missing item only for it to arrive afterwards

I sent an almost £50 item to someone over Christmas in 2nd class recorded delivery, around the beginning of December, but after a couple of weeks of no delivery they opened an A-Z and I ended up refunding them for it. Over 3 weeks later from when I posted the item, it was delivered according to the tracking number, on the 2nd of Jan with a signature.

I have since tried getting in touch with the customer via Amazon messages with no response. They were in continual contact with me about the whereabouts of the item before the refund and seemed courteous enough, but I haven’t heard anything from them since their message thanking me for the refund. Nothing to say that the item eventually turned up and no responses to either of my 2 messages spanning the last 5 days or so. They previously said that it was a Christmas present and was no longer needed when it failed to arrive before Christmas. Now it’s suspiciously looking like they are hoping to keep it for themselves with a free refund.

What’s the best way to approach this? Would I have any luck appealing the A-Z seeing as it has since arrived with a signature? Whether I get reimbursed for the money or get my item back, hoping that there will be some sort of fair conclusion.