Now, they do actually attempt to give you a chance to fix your overusage by warning you once, except in my case, they warned me half way through the month, and then shut me down for the good the next month due to the traffic that had gone out before they warned me. They warned me in a way that they were unable to measure the drastic traffic decrease after I fixed the problem, and they had to shut me down anyway. Their support people actually acknowledged that in my case there was indeed nothing I could have done, but they also said there was nothing they could do either due to the way their system works.
Until they fix their warning system to match logging cycles, or honor the one month grace period they promised me, and then pretended they never had, I can see how they're going to get many other people shut down that way.
If comcast is actually meaning to give their customers a chance to fix a usage over an arbitrary limit they won't disclose, they have some serious fixing to do, starting by not putting their customers in the criminal/DMCA pile that their regular support folks are not even allowed to help."