I think you'd better complain Comcast to FCC first. It works.

You can do it online through FCC website. I once got unreasonable charges from my phone service company, then I complained it to FCC and I got the pretty good result -- they sent me a letter to appologize and withdrew all the fee charged unfairly. Believe me, such companies are scared of FCC very much.

Tell them you refuse to pay and are going to complain them to FCC and do do it. Then you can wait and see their response.

Good luck!