don't trade with mdomin, he will go red and not return your money, and will not respond to PM's
have you contacted a moderator? They may be able to help.
I've been dealing with mdomin for a while; his trading privileges were suspended over a week ago, his TR set to -1, and his rank changed to "Do Not Trade With Me."
He has refunded a few people, but I wouldn't be surprised if he's finally just given up. He made a rookie mistake on a lot of trades, and I think it probably cost him a couple hundred dollars.