From the FCC FAQ web page on cable complaints:
How can I file a complaint against my cable company?
Complaints about rates or service should be directed to your local franchise authority. A franchising authority is the local municipal, county or other government organization that regulates certain aspects of the cable television industry at the state or local level. The name of the franchising authority may be on the front or back of your cable bill. If this information is not on your bill, contact your cable company or your local town or city hall.
In addition,
filing a complaint with the FCC is very easy as this referenced link shows!
Good luck,
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