I envy your luck. I've had non-problematic experiences, but also several negative ones, including one that I (hopefully) resolved after many months.

Most of their support staff are friendly, but rarely helpful. One or two have been actively horrible, but that's not the norm.

To date the big events are:

1. I started having some lag spikes, and after the normal troubleshooting, they scheduled a tech to visit as the issue was probably my cable modem. Want to guess what the tech DIDN'T HAVE WITH HIM? (And not a "I swear i loaded one I'm so sorry" but just a "yeah, I can't even say if it's your modem since I have nothing to test with. Do you have another we can use?"

2. The problem was the modem, so I bought a replacement. After a while a modem rental fee appeared on my bill. I called, they apologized and removed the fee. It silently reappeared the next month. I called again, and they said the serial number was in their inventory as theirs, so reality didn't matter.
After a couple of more tries (never assume anything the person says is accurate. Even "there are no notes about that on your account") I was fed up enough that when fios became available I jumped on it. While cancelling the service the guy was apologetic about the modem mix up, removed the last months fee and I wasn't required to send them my modem, even though it was clear I wasn't going to change my mind. headdesk

3. Now on a new coast, I go to cancel my rental service when I buy a house. Friendly rep said it was taken care of. 2 months later they are calling me about a bill because the service was never cancelled. So I pay, but I'm very thorough in making sure they say it's done. Another month, another bill, and the account still isn't cancelled. This guy was an ass, and it was a waste of precious time repeating myself to him, so I asked what it would cost to be completely rid of them. I paid that money, confirmed very explicitly that there was no other reason to interact with them ever again, and verified online a few times that my account was indeed cancelled. That was the end of October. Last week I get a call from a bill collection agency, Comcast says I owe MORE money.

First call is a waste of time - no sign on my account that I had previously called, says that I owe for the month OF my cancellation, refuses to transfer me to anyone and offered me the phone number FOR VERIZON!.

Second call was much the same, but I demanded they make a note that I said I had previously cancelled. But the reason I "owed" the money was suddenly different.

Third chat was online. Absolutely no difference other than not having to deal with their infuriating voice system. (Pet peeve: systems that ask for account numbers, but don't give them to the support person.)

Fourth call I just explained repeatedly that I would have to be transferred to someone because I wouldn't even pay to get rid of them, since that doesn't work. I also mentioned that I had the complaint forms for the FCC and BBB along with Twitter all open in my browser, ready for use. No idea if it was the threat or just my persistence, but she had her supervisor "pull my account" (which at least one prior call had said they had done) - she saw my list of angry calls, but as she tried to walk me through why I owed money, she noticed a request for cancellation on Sep 1. Service was actually Nov 5. Suddenly I don't owe anything.

Tomorrow I check to see if the bill collector has been called off, then to see if anything has made it to my credit report either way.

Whole thing consumed several hours of my life, but it's not worth my time or the blood pressure to pursue further correction.

I vowed that if monopoly ever required I work with Comcast again, I would record every piece of data - dates, times, confirmation numbers, and I'd also callback immediately to confirm the notes on my account. Basically don't just assume stupidity, assume malice. Assume that anything they said was a lie until you prove otherwise, because that is the level of prep needed, regardless of whether it is malice or incompetence. With luck I will never have to.

Comcast heard Time Warner had displaced them as having the worst customer service as was all "hold my beer". Ugh.