Virgin charged me £10.80 too much this month. The telephone customer service person agreed that a mistake was made, but was unable to rectify it. She then tried to transfer me to the "proper" customer service department, but the call got cut off.
The exact same thing has happened to me. Also i have noticed that i have been charged a differet amount to the amount stated on my contract for over a year!! I have made a complaint online as i cannot get through on the phone.