Why is my $40 plan billed at $89?!

I moved and was at the end of a 12 month deal where my service was $34.99. When I moved my rate was supposed to be $40. I got my initial bill after the move for $89, and the agent said it was a gross error and my bill was adjusted down to $44. I'm rounding. Now my plan is still $40 as it says on my account, however I'm being billed $89 for a $40 plan. I have grown sick of calling every month to possibly be charged the correct amount, as I've been promised many credits that were never applied. I'm being told this bill is accurate now for equipment. I have no new equipment and everything is included in my $40 plan. Why won't Comcast take any accountability? I can't wait for google fiber to finish being installed in my neighborhood. [Edited: "Solicitation"]