Cancel by post (recorded delivery) by sending your 30 days notice to the address at section N of the T&Cs. You should expect no acknowledgement of the cancellation - nothing, no email, no letter, although they will soon start making customer retention calls to try and offer you deals and promises that they wouldn't have before you cancelled. If that strikes you as a waste of your time, you may want to state in the letter that you do not wish to be contacted by customer retentions, sales or "market research" callers, although only time will tell if they'll respect that instruction.
I had five incoming calls from VM on my last day of connection, all in the hope of persuading me to stay with them. As an aside, isn't it strange how VM can afford competent UK staff for sales and outbound retentions, but most times a customer has to contact them its through cheap offshore call centres staffed with barely trained, disinterested slaves? Says something about the value they put on customers when their in a fixed term contract.
Note that due to the incompetently designed billing processes, you may to be billed again AFTER they've disconnected you because apparently 30 days isn't enough to finalise an account for this company. My broadband connection finished this Wednesday and they'd previously sent an email saying that on Thursday they would be billing me for the next month, and that included a phone line charge for a line that was ported out six weeks ago. On the day I can't see anything was taken out, My Virgin Media shows a bill of £00.00 for February (and a payment due date of 1 January!), but still a credit for £10 or so which I assume will be sent as a cheque for the outstanding balance in several weeks time. So I think they have got the billing roughly correct, that in fact I wasn't billed for a month I don't owe, but the clarity of pre-billing communication is outstandingly poor and inaccurate, and despite having my bank details to make an electronic credit they're going to use long winded and slow (and more costly for them) cheque process.
