The best you can do is to refund the cost of the article, but the customer must be aware that they have to pay return postage. faulty goods, goods not as per description. etc are returned at sellers cost, but if the goods were " as described" then the buyer is able to return if they pay return postage. Ebay/paypal are always on customers side and will probably freeze you payment until the issue is resolved, so be nice to the customer, but point out that they knew the situation before they purchased, and that you have stuck to ebay guidelines etc. I must add, I have two ebay shops, feedback 7000, and occasionally you get the idiot customer.
Annie.