Ask for their final response, then either contact their CEO team <Executiveteam@virginmedia.co.uk> phone 0800 052 1569.
Or take your complaint to CISAS (International Dispute Resolution Centre),
www.cisas.org.uk which VirginMobile and VirginMedia are members of.
I had two separate complaints with VirginMobile and VirginMedia this year and CISAS upheld both my complaints in my favour. Get all the facts together and complete their on-line form. It normally takes 4 weeks to be resolved, but before you get a response from CISAS, Virgin's CEO office will be on the phone with an apology and for me confirmed a refund of monies due to me!