How to block a bidders from Your eBay Auctions
If you think you have a bogus etc user bidding in one of your auctions, you can block that user from bidding in any of your auctions.
To do this:
Go to the Site Map page and click the Blocked Bidder/Buyer List link.
When the Bidder/Buyer Management page appears, scroll to the Blocked Bidder/Buyer List section and click on Continue.
When the Blocked Bidder/Buyer List page appears, add the buyer’s user name to the list.
If you want to add more than one user separate multiple names with a comma