Cancel the bid.
Simple, cancel the bid. Go to My Ebay, go into selling, follow the promps. You can block or pre-approve bidders in your auctions.
You can cancel any or all bids, and start the auction over (you will incur Ebay fees - of course!)
Always have very specific terms in your auction to protect yourself - item as is/where is, no returns, etc.
Aloof with hermit eye I scan
The present works of present man
A dreamlike trade of blood and guile
Too foolish for a tear, too wicked for a smile -- S.T. Coleridge