I hated cancelling accounts or services, because the people you have to talk to insist that you stay, and offer all these things for you. And if you have a hard time saying "no", then they almost guilt trip you into staying.
I found that just saying "please cancel my account/service, I don't want any of your bullcrap. I know you're just doing your job, but I dont' want it anymore", usually works and ends the conversation.
I think the next time I cancel something, and have to call someone, if they start talking to me about all these things I could do to stay on, I'm going to start telling them about stories that don't lead anywhere or make no sense, so that they'll want to hang up on me lol.
I think companies are developing these tactics in response to people leaving or because that's the best time to offer them services they don't really need. That's probably why new credit cards and stuff require you to call the company to activate it (I've had to do that with a Sears card and a Best Buy card now), and both times the people I talked to tried to offer me a program which I didn't want (I could've just hung up on them, but I didn't want to be mean). Used to just be that you could dial your card number into an automated system, then the card would be activated then and there in contrast.
I did interupt them and ask if my card was activated though, and once they said it was, I told them that's all I wanted, then they thanked me, and hung up

I think next time I have to do that, I'm going to say "thanks" as soon as they tell me my account or card is active/cancelled, then just hang up. Yeah, it's mean, and they're just doing their job, but ugh, stop making me pay for more crap I don't want lol.
Jam it back in, in the dark.