Talking of call centres, one of my pet peeves is how easy it is to sign up for services and utilities online, but for them to not allow you to cancel that service online also. Forcing people to phone up to speak to someone who's livelihood depends on people not cancelling is a cunts trick and it should be illegal.
It should be law that if you can sign up for TV/Broadband/Phone/Insurance/etc. with a few clicks online, you should also be able to cancel them with a few clicks online. By all means keep the call centre as an option, but if I visit the "Manage my account" page, I expect to be able to fully manage my account. Big red CANCEL button front and centre, not a phone number tucked away on some obscure FAQ page.