Bill higher than promised

I had a promotional rate of $85 for two years. The promotion was ending in September. I got a call on August 16th from Xfinity offering $95 per month for the same internet plus XFI Complete with no contract which would be cheaper than the increase when my existing promotion ended in September. I agreed. I just got the new bill and the monthly rate is $117.

I asked multiple times on the call: "Will my final rate be $95 per month?" and every time the answer was "Yes."

Why was I told the incorrect amount?

How can I either revert to my original rate of $85 or get the correct rate of $95 for the current service?