Yep, my franchise is Bromley too & I got two account numbers due to an NTL error when I signed up.
They sent me my ordinary BB bill plus a separate £2 bill with a different a/c number for not paying every month by DD - even though I do.
One of the regulars here who worked for NTL C/S sorted it out for me - another good reason for joining CF
If it becomes an issue for you just contact C/S - and if you have no joy with the standard route post here again & I'm sure one of NTL's serfs who surfs here'll sort it out for you by PM