Unhelpful support & fraudulent billing

I have tried multiple times to downgrade my service and received confirmations each time, including the shipped kit confirming the new service, but am still being billed for the old more expensive service. The website, what little of it chooses to load or function on a given day, indicates I have a 150 down and 100 up plan. I currently struggle to buffer 360p videos, which would sure seem like I am on a slower plan as selected. I am not interested in troubleshooting connection issues or being offered various plans to keep my bill as high as possible, I do not need any of this. 

I went through a multi-hour fight last month to escape the robot and actually talk to a human on the phone, who claimed to have then enrolled me in a 12 month commitment to the cheaper plan I had already selected. He claimed to "open a ticket" about getting refunds for the erroneous charges, but I was unable to view any details on this other than a notification that a ticket was closed shortly after with no change to my account balance. I will again stress that I have evidence that I initiated and succeeded at changing the plan, only for Xfinity to revert this with no notice and continue charging me their preferred amount. I have now again been billed 100$ for a plan I have tried multiple times to change, not even cancel, just change. I am now disputing the transactions with my bank, and will be cancelling my internet and mobile plans entirely if this is not fixed. I will not communicate about this with the bot or phone service again, as they have failed to correct this and lied in the past. Xfinity can communicate about this in a way that leaves evidence behind or lose a customer.

Locking out my ability to change plans on the website after the first change conveniently reverted to a more expensive plan, to make me use the chat, to then make me use the callbot, to eventually have a person directly claim to have enrolled me in a different plan, and to still have me on a different plan than I selected is fraud.