I saw this around last year when the owner of the domain Nosepilot.com was trying to fight it. I believe he won the case because they did not give him any prewarnings to this letter. When he registered with their company I believe there was no limit on bandwidth, and after they sent this letter they changed their policies. He ended up being told that he owed that ridiculous ammount after they changed it (without telling him, so his bill would keep growing). Anyways, to make a long story short, he got a lawyer and was going to take legal action, he had all the documentation that said there were no limits when he signed up. The company ended up dropping the charge.
This is all from what I read on his site last year when he was having these problems. I don't know if he is still around however.
