Are you saying that every house in the new development is on it except yours? That is strange if so!
Either way, the first line staff will usually just stick by their database. If computer says no then it is a no!
The best way to go forward would be to contact
cablemystreet@virginmedia.co.uk (I think that is the address). They are the team that look into the viability of cabling an area and come out and do surveys. So if you explain to them the situation and tell them the ducts and cabling have been put in already they should be pretty quick to sort it all out for you, unless there is a reason why they can't connect you, in which case they should tell you why.