Xfinity fraudulently changed my auto payment info

I have auto pay set up on my account. For the last 2 years my monthly payments have been taken from my bank account. Happen to check my email and I see an email saying my payment has been declined and I’m late on payment. I go into my account to see that Xfinity somehow changed my auto payment method from my bank account to SOMEONE ELSES VISA CARD. No clue whose card this is. It’s not mine and I am the ONLY PERSON ON THE ACCOUNT. How did this happen??? I have not made any account nor billing changes, so I did not authorize this in any way. This is a fraudulent change and breach of security. How does someone else’s credit card suddenly get added as my billing auto pay?? For days I’ve been trying to contact Comcast to resolve this issue. Can’t get a live person on the phone and the online chat agents aren’t helpful in the slightest and continue to transfer me to other people then ultimately stop replying. Extremely poor customer service. They are not understanding I have not authorized this account change and management needs to be made aware as this is a serious issue. I’ve spent several hours of my time trying to explain the issue and wait for responses and just keep hitting a dead end. The worst customer service on the face of the planet. Someone please help!!! I need to speak with a live person ON THE PHONE.