You can also opt out online just search telephone preference service

took about 3 goes for me sending the stuff back to their customer services. I can't remember if I put stamp on or not

Gather together the Virgin junk mail, write on it I do not want this junk mail. Send it back in one of there own envelopes to Virgin media, PO Box 333, Matrix Court, Swansea, SA7 9ZJ . Keep doing so as it may take more than one attempt but eventually they get the message and stop sending things to your address ---- yes even stops the ones addressed "to the occupier"