My friend sells on ebay and she sold something to someone abroad, guessed at the price, and postage was actually £2 cheaper than she thought. The person emailed saying she had ripped him off (it wasn't a polite email either) now as a principle she will not refund the difference, she would have done if they had gone about it differently, anyway they are saying they will report her to ebay and she is worried she might get kicked off, I also sell on ebay and don't think that they actually would as she said the costs before he bid.
Anyone complained and got nowhere, somewhere?