Have to call it in and give 30 days notice, Call “Retentions” on 150 or 0345 454 1111 - options 1-1-4-5 "Thinking of leaving" - they are open 8am until 10pm [calling early is usually best]) you will usually get a UK call centre and they will sort it for you.
-------------------- Services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.
Be aware that if you've signed for a year, that's what they'll hold you to - so if there's a couple of months left, they'll still insist you pay that, even if you're not using the service. There's no way of avoiding that. If that causes difficulty, just bite the bullet and pay up. Don't cancel the direct debit and hope VM will go away - VM will treat the unpaid months as a default on a credit agreement, and that will ruin your credit rating for years to come.