Issues cancelling service

Hi, I am @harshm747 i had xfinity internet in my college housing for a year, and had requested to cancel service when I graduated and got an email saying that 'we have received your cancellation request' ; i tried to chat with two assistants who assured me my service had been stopped. Today I get a mail from xfinity saying my next payment is scheduled for next month as my service is not cancelled. I have tried everything I can to cancel my service, but xfinity doesn't seem to cancel it. What can I do? Please assist me.