Buyers seem to think they can return anything today. Which of course they can when buying online from business sellers. Plus no-one seems to read conditions, returns policies or even item descriptions these days! Are people becoming more childlike? Or is it just that everyone uses tha app today, and the small print is just to small to bother with?
Anyway, it's your call. You can refuse the return, in which case you can expect at least a tantrum. More likely the buyer will suddenly remember that it was not as described in some way, and open a case under eBay's money back guarantee. EBay will support them, they never see the item and will take the buyer's word against the seller's.
At least they've paid the return postage themselves. In your position I'd grit my teeth and send them a cancellation request through the resolution centre.
