After you get it back you can report the buyer to ebay. Buyers misusing returns is classed as abuse and you can report that here:
https://www.ebay.co.uk/help/policies/rules-policies-buyers/buying-practices-policy?id=4374
And be sure to put his ID on your blocked bidder list:
https://www.ebay.co.uk/bmgt/BuyerBlock
Good luck.
