Turned off Autopay but it charged me anyway

Hello. I canceled my Xfinity service around Christmas and it is now January 8th. I disabled autopay and requested that my card details be removed. 

After ending my service I can no longer view the pages for my bill details or my card details. I would usually pay my bill around the 23rd of each month, through autopay. I also returned all equipment already and wanted to fully close my account. 

Today, January 8th at 3am Xfinity autopayed itself $40 from my card. Everything on my account said that I owed $0, and I removed the autopay feature. 

I didn't authorize this, and I can't even view any details as the page constantly comes up with an error. Chatting with an agent does nothing because they take 40 minutes to reply and then just disconnect without doing anything. 

I do not want autopay, I don't want you to have my card details and I don't want charges without my consent and knowledge. How do I turn all of this off