You signed a piece of paper. Buried in that piece of paper was a contract of some kind. This is how they get you 'low prices' and then a year later jack your rates up like nobody's business.
As far as them being the only option in Waterloo, you're right, and believe me, I hate that. During the summer months, my cable's all good, no problems whatsoever, but once it freezes, forget about it. Constant interruptions, everything disconnecting frequently, losing service multiple times a day. Yeah, it's ugly. Called and complained, yup, they don't care, or just won't fix the problem.