Charged late fee with autopay??

I have autopay setup and have been getting money taken out of my account automatically for almost a year for my Comcast bill. Today I get a call saying that I owe over twice my bill and that my service will be discontinued because I didn't pay last month. How is that possible or my fault? Why wasn't my bill payed automatically like it has been for almost a year? Why wasn't I notified? It is impossible to get anyone on the phone to ask these questions to. This is robbery. I am being robbed. I can't cancel my service because I have to work from home. Comcast is using the current state of affairs to rob people.