how do i block a bidder from bidding

[santatree5]

I sold an item the buyer never paid and never returned my messages. When I relisted he bid again

[woodland_gnome]

You add him to your Block Bidder/Buyer List.   Go to the Site Map (link at the bottom of this and most ebay.com pages) Sell Section (use the shortcut at the top--it's a long scroll down) and you'll find the link to that and several other useful seller tools.