I think ther OP is saying he has cut the incoming cable to the master socket from the omni-box outside, which is Virgins responsibility.
Oh, I assumed when the OP said 'We have been decorating and accidently cut the white cable coming outof the Virgin phone line boxin the house' that it was the phone lead from the master socket, not the lead to the master socket.
This is certainley what VM will have assumed if they are quoting the non-fault callout charge for cabling that is not part of their installation. The OP needs to clarify the situation, or they will be booking a needless callout.
PS I have seen VM installations with white cabling feeding the master socket.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV6), Talk Anytime Phone, VIVID 350, Virgin PAYG Mobile