Frustrated customer here

I had been on the Connect More plan (mobile+Wifi) for $41.85 per month and was completely satisfied. This month, my bill jumped to $143 without any notice. When I called Xfinity, the first representative told me that I had supposedly called on 9/11 and manually authorized a change to my plan to 1000 mbps. They said they would open a ticket and follow up within a week. After waiting a week with no update, I called again. The second representative said there was no open ticket and claimed the authorization happened on 9/8 instead. I did call on 9/8, but it was to dispute the previous charge, not to change my plan, and I have repeated that explanation multiple times (spent 2 hours on the line, explained at least 5 times today) without being believed. Xfinity applied a $40 credit ($20 each, twice) to the $143 bill, but my Connect More plan has now been removed, and I am being told my new monthly charge will be $65.69.

All I am asking is to have my original Connect More plan restored at the same $41.85 rate and to have the overcharge corrected. I have already made multiple calls (spent total 4 hours on the line for this issue) and received conflicting information and dates. I requested ticket numbers, but none were provided. I also asked for an escalation, but I still do not have a resolution. I also qualify for student deals, but it's not working on my end either :( Who should I talk to...?