I can understand that the seller wanted to increase his sales by using a fantastic cover. But of course this is not the way it works.
It's also dangerous, since EPE might think Unchained (or other designers) are co-operating with these sales.
Perhaps it's a wise idea to mail the seller first with a kind request to take away this cover and that you're otherwhise forced to contact Ebay about this. Big chance that he will remove the cover.