kaled - 1:55 pm on May 5, 2010 (gmt 0)
Without more details, only guesses can be made. My guess is that your best course of action is to forget about it and move on.
In the case of a physical auction, when the hammer goes down a contract is deemed to exist. So far as I am aware, online auctions do not carry the same legal mandate and unless you can show that a contract existed, you are not likely to have a winnable case.