question Can I ban a certain member from my auctions?

I had very negative experience with one of my auction winners. The deal took quite a long because of NetSol sending auth codes, and this guy pm'ed me every few hours, and then threatened me with mods and everything, and finally he said he can give me only negative rating.

Naturally, i don't want to deal with this scumbag anymore. Can i ban him from my auctions, or disqualify his bids?

Also, is there a subforum here where i can tell people about him?