The new contract term is in the
T&Cs:
If we agree to provide the services to your new address, you may have to pay a service transfer charge (to be paid to Virgin Media Payments). Details of the service transfer charge are set out in the price guides. We will also send you a new contract for the services at your new address and you will have to keep the services for the minimum period. The service start date for your new minimum period will be the date that the services are installed at your new address. You may not be able to keep your phone number if you move house.
So that's why you would be charged Early Disconnection Fees. Whether you could dispute this would be between you and Virgin Media