Comcast would not let me cancel. It was the old America Online Trick. I had to call them many times over a period of 90 days. I spoke to several different people at a time from India to who knows where and waited on the phone for them to pick up.
They kept saying all clear, you’ve been cancelled. And the next month i would get another bill.
I finally went on a marathon and would not give up. I pestered them for days until they finally canceled my service for good.
Let’s just say they are my isp of last resort.