Your contract doesn't start until your account is activated and connected to the VM network. So you shouldn't need to cancel anything from a financial perspective. But if they send a quick start kit you will have to send it back so best to cancel. You can only do it this way...
1) Call 150 from a VM phone or by dialling 0345 454 1111 - sect options 1,1,4,4, from any phone - they are still picking up (in the UK too) - calling at 08.00 is the best time to get through with short wait times and getting the UK based retentions team - at busier times they may forward calls to offshore CS
"TOP TIP (not tried myself) but If you're struggling to get through or are tired of waiting in the queue - you can try Virgin Media's cancellation and retentions department directly on…. 0800 952 2277 or 0800 052 2001
2. Cancel In writing to…
Include dates, name ,address and all your account details. They say to also include your phone number so they can call you to confirm - probably to make you an offer to stay.
Do it by registered mail with a receipt for signature on arrival.
3. Or if a new customer in the 14 day period - completing the cancellation form you have been given as part of your welcome quickstart pack and returning this to us at the address specified on the form..
I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired, 1 WiFi, 1 on PA) Hub5 in modem mode with Apple Airport Extreme Router +2 Airport Express's. On 250Mbps, Talk Anytime Phone, x2 Mobile SIM only iPhones.