Well there you have it webster74. VM value your business so much that as far as the staff are concerned you can sit on your duff until the end of time waiting for a Whatsapp response, and that's normal and acceptable as far as they're concerned.
I'd say cancel by recorded post to Virgin Media Sales Operation Support, Virgin Media, Sunderland, SR43 4AA
If you want a new deal then they'll be busy calling you during your 30 days notice period, and if you hold out for the same sorts of deals they're offering new customers eventually they'll offer those. if you decide that you're entitled to better customer service than this, then just let the cancellation run nits course, and choose another ISP according to what you want to pay and what sort of service you want. If customer service counts then at least consider smaller ISPs like Zen Internet, Aquiss, uno, IDNet, AAISP (who mostly don't have price rises in fixed term deals, and some of whom offer only 12 month fixed terms). If you want the sort of "pile it high, sell it cheap, and then give the customer a price wedgie during the 18-24 month fixed term" deals that VM offer, then BT, Vodafone, et al are the suppliers to consider.