Canceling service kudos

I called one of the "loyalty" representatives to cancel internet service several weeks ago because this was my only option. They informed me it was canceled after trying the script to retain me as a customer and informed me of the final billing amount.

Couple weeks later odd billing issues including being charged for the next service period after cancellation with late fee. Had to call back to rectify this and was told it was an accident and given a different slightly higher final amount than the first representative. Something about services disconnected earlier but cancellation date input as later date. I don't think my brain was able to process how these could be different, but I have given Xfinity a lot of money for nothing for awhile now. Maybe an actual mistake but the phone bot did ask me to pay the 3x higher bill several times before I waited 30 minutes on hold to connect with a human being. 

Is it too simple or just not lucrative enough to just let the customer cancel themselves online? I just wanted to compliment Xfinity for the unethical/shady business practices. Like if it wasn't bad enough using the services here's some aggravating logistical nightmare to finally disconnect. Crazy work.