If you've been billed on the 3rd Feb, then your notice ran out 30 days later. This part of the terms apply
http://store.virginmedia.com/the-leg...es.html#ending
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If you were not notified of these changes in advance, you must give notice of cancellation of the services affected to us and/or Virgin Media Payments (as applicable) within 30 days of receipt of your first bill following such increase in charges.