Make sure to file a complaint with your state attorney general. Cases like these can quickly get their attention and more importantly, companies don't want to be investigated by AGs. Unlike state regulators, companies are less likely to have a pre-existing relationship with them. Since you're talking about telecom and not just internet, it's also worth checking to see if that is regulated by your state PUC/PSC. Don't bother with the better business bureau. A company can have an A rating as long as they respond to you, they don't actually need to fix your issue.

Also file complaints with your city. Comcast relies on licenses from the city to use the poles for their cables. Complaints about bad service tend to get fixed quickly when their franchise agreements are in peril.

The best way to cancel any cable service is to simply unplug your equipment and drive to the service office and plunk it on the counter while announcing loudly that you’re canceling your service. It took all of 15 minutes and all the service rep said was “Sorry to see you go.” No retention techniques, nothing. It was the best customers service experience I ever had with Comcast.

In my experience helping an elderly relative with the cable shitshow, the Comcast service center people are actually really nice and would have done so without the drama. But I definitely recommend the physical side of things.

Although I have done a bit of a chaotic neutral thing myself: Comcast sent her two new boxes instead of one after we switched her to a cheaper box. They wanted us to drive all the way back to service center. Grabbed their UPS account # from the tracking code, filled out the web form and had it sent back with pickup billed against Comcast’s acct. She never got billed a cent.

I recall a similar experience after cancelling over the phone.

I went to the store to return the box and they said I'd have to take a number.

I said "Nope, here's the box I'm returning, we're done here". Took some pictures and got the F out.

Returning something shouldn't take more than 30 seconds. And it wasn't going to take more than that for me.

Depending where you are in the US, you're in for an hour or two of waiting.

Another way to deal with Comcast is to go in to their local customer service office. The people there are real, live in the same town, etc and generally can solve any issue and will do so with no BS. At least that's my experience.

When I've tried dealing with someone in their call center, it's been much more frustrating.

Unfortunately sometimes they’re woefully understaffed. When we lived in New Haven they never had a line less than 20 deep and it was clear that they just needed not to skimp on staffing because the people were working as quickly as they could.

It's more like the DMV, pick a number, sit in the large waiting area for 30 minutes, just to get someone who doesnt really want to be there either.