Yep... it's an utter con........... I recently moved out of my old address which I have now given over to a student but I have agreed to pay for Broadband as part of the tenancy. We thought the simplest way to do this was for me to take the cost of BB off her rent, but change the VM bill to be officially in her name, this way she was liable for the bill if she decided to plug in a phone and use it. In turn, she didn't want to be locked into a new contract the main reason being that as a student, she may only be there for 9 months.
Oh the hassle on trying to do this! I phoned VM and had different people telling me different things. One person told me all it would take is a phone call, and that it could be done on that day, next I had to fill in a TOR (transfer of responsibility) form and that had to be filled in by both parties. The TOR forces the other person to take up a fresh contract (12 months minimum I was told), and they are charged £20 for the priviledge.
In the end we settled for adding her name to the bill (but not taking mine off), and transfering the Direct Debit to her name and bank account.
There are all sorts of circumstances I'm reading about where a change of name might be the simplest solution for many people, especially if they haven't finished their contract but VM just don't allow it. On moving out I found the Electricity, Gas and Water companies I was with far more flexible about this and happy to change the name, I hear even BT are ok with it but not VM. They prefer to charge you and set the next person up with a contract. In some cases a transfer is more expensive than changing phone providers altogether (some have discounted installation costs) so my advice is shop around.