Personally mate i'd refund the money back, and open a dispute (which you are quite within your rights to do), you say he's knocked £6 off the total, and hes from abroad.

Ive bought countless items that people havent actually wanted to sell, and albeit a legal obligation, if you win and they dont wana sell it theres fuck all you can do about it.

And as for the negative....if he leaves you one, you leave him one. Hence why when i sell an item i never leave feedback until ive received it, works very well as you don't get spiteful cunts leaving you negatives hastily

And as said you need to set up your bidder requirements properly