Comcast works the same way as Time Warner, you have to call and complain to get anything done. TW will reduce bandwidth over a line and see how much they can get away with before people start calling in.
Go to http://www.pcpitstop.com and do speed and packet-loss tests. If either aren’t what you have been promised call and complain. If they give you the loop remind them that you are the paying customer and can call the FCC and file reports of them not fulfilling promised services to customers. If they have a monopoly on service in the area then that will be an extra kick to the groin because utilities that have monopolies on service in an area are held to a higher standard than those that have to compete.