[sssshhhh]

you should call NTL as you have a 6 pair cable going into your house, but from what you have described you have the blue cable which pairs with the blue-white is missing. The tech will need to match the colours up in your master with the colours that are connected in the box on the outside of the wall (and they are usually use the blues). He'll also be need to krone in your extensions properly to make sure these are working as there are various ways they could have been connected originally. Good luck