I haven't had any real issues with canceling the few things I've needed to. The only major ones I had to call in for were Earthlink and MSN dial-up internet services, and overall they were pretty easy to work with. The person from MSN sounded almost sympathetic when I told them the internet service was too slow and I didn't have broadband available in the area.
I can't say the same about when I've had to call for tech support though. Most of the time the tech support people from India that you'll almost certainly end up talking to don't have any knowledge of computers whatsoever (yeah yeah, elephant in the room). My friend had called in about his computer having all kinds of issues: random blue screens of death, programs crashing, static over the speakers, etc. and after taking several minutes to explain all the problem, the Indian tech support guy went "...have you turned on your monitor?". Oh well, at least when I needed to activate Windows XP over the phone I didn't have any trouble and the person could speak English clear enough.
On the other hand, you might end up with someone like this:
http://youtube.com/watch?v=dxq3zJ8djo4
Jam it back in, in the dark.
85242
35212
Solis