It's not right of course [although it is "possible" that the seller had two]. Sadly there is no way to enforce a seller to sell.
All you can do is get your money back if not [through the resolution centre] and leave negative feedback in simple terms such as "Seller would not honour sale". No abuse!
I hope you have paid, then if seller does not know the correct way to refund you they still end up paying the Selling fee which would be about £64, that would teach them a lesson.
