Worst customer service I have ever received. Where can I leave a review and complaint?

Comcast has wasted over 12 hours of my time and have not honored anything I have been told about my bill.  I have called and spoke to several of your representatives.  I even spoke to a supervisor who promised to call me back at an agreed upon time to make sure the issue was resolved.  I waited for the call, but it did not come.  I saw that he called me at another time, when I was unavailable.  The issue was not resolved, as promised.  I have included a letter with my bill.  i have made an appointment, and visited the store, to resolve this billing problem.  At the store, I was told they could not help me, even though I listed why I was coming in.  I was told I had to do a video chat with someone who could not understand English and resolve the issue.  After that visit, I was told that I added a service.  That is not true.  I was originally promised a price when my plan expired.  It was not honored.  I was then promised another , higher price, and it was not honored.  Late fees and extra fees were supposed to e be taken off my bill, because of Comcast's mistakes.  This has not happened.  I have been a customer for many years, however, it is obvious to me that Comcast does not care about my business or my time.  You make it almost impossible to find a way to communicate with you.  I am finished wasting my time.  I will continue to honor my commitment.  Even though Comcast has not honored theirs.  I will be looking for other options in the future.  This is, by far, the worse experience I have ever experienced with any company.