I mostly just want to whinge so please indulge me.
I cancelled my phone contract with O2 in early June. Customer services told me I had to pay for the handset first so did this with credit card. Got email later on billing date telling me no payment due.
Yesterday they sent me a really shitty letter saying money was still owed on the handset but as I pointed out on the phone to cust serv yesterday a) they wouldn't have cancelled service without full payment, so what do they think was the purpose of said credit card payment and b) they sent email confirming no payment due.
They acknowledge that they ended service at end of first week in June.
They agree to cancel outstanding sum that they think I owe (even though I do not) and to send email confirming.
Today I get another shitty email claiming I owe money and threatening to cut off the phone that they have already ended the service to. When I email back they bounce my reply back to me on the grounds that they have shut down their customer care dept! Evidently 
Why the fuck can't departments talk to each other before sending out random snotty communications?
Feel better for the rant. But seriously what are they thinking in sending a threatening email that I cannot reply to, the day after agreeing that I owe them no money?
If anyone has any tips for dealing with 02, they eould be much appreciated. I cannot face phoning them again tomorrow.