Unable to correct address error on account

I have been trying to correct the address on my Virgin Media account since I moved into my new build property over a year ago.  When I moved into the property I was told by virgin media that the postcode they had for the property was correct and the one I use for every other utility and the one on the title deeds was wrong.  I was advised to sign up using the incorrect postcode and it could be sorted at a later date.  I have subsequently tried in several occasions to change this error but have got nowhere.  I have been referred to several departments but no one seems to be able to fix. Does anyone know how I can go about getting this fixed?