We don't have "bid retraction" because sites with it are shill bidders' paradises. Make a "mistake", retract it, later have a friend bid just under the high bidder's maximum.
We recognize that people make mistakes, so we look at the bid history, confirm what they said is what occurred (I have had people make five bids, and then claim the last one was an "accident"), and then we cancel the auction, and we re-auction the item. A real hassle for the consignor, because they don't get paid for a couple more months, and of course the item can go lower the next time, and of course we have to do twice the work.
We note the account of the person who did it, and if they make another such mistake, we tell them they have to bid elsewhere (and the person can't simply open a new account, as is true just about everywhere else). We want everyone to know they are always bidding against real bidders who 100% of the time honor their bids, and this policy goes a long way towards making that happen.
E-mail us the details and we will get it cancelled ASAP, and removed from your account. And please be careful in the future.