Apparently, Ebay has decided that despite the seller still possessing an item, and my money, that the seller is entitled to keep both because they supplied a tracking number; the same tracking number which shows the item was delivered back to the seller, who now has the item in their possession and not mine. Ebay will not accept an appeal, and I am out-of-pocket.
I am now withdrawing all my items for sale from Ebay since they seem to think that it is acceptable for a buyer to receive absolutely nothing for their money.
The seller in question is 2015-metri, aka Stanislovas Metrikaitis (email@example.com). Should have checked the negative feedback on this fraudster before bidding.