I need help with this same issue. Most of my neighbors addresses show up but ours doesn't. According to our housing association we should be connected and that it may be an address problem. Contacted BT customer service and the girl was of no help whatsoever. She basically just said your not connected to the exchange because our address didn't show....which we knew already. She didn't offer to look into our query amd we were dismissed.
Do you live in a new build? Are you paying council tax? Are you on electoral register? are you getting post from Royal Mail? If you say yes to any of these things then you should be on the National Land and Property Gazetteer (NLPG) - this is managed at a local level by your local council - there will be a local address gazetteer custodian, somewhere in your local council (Local Land and Property Gazetteer - LLPG).
once you're on any of these systems, it should filter through to all the others. Royal Mail use the PAF (Postal Address File?) - again if you're on that, then your address should be visible on the system BT use. If not, then BT haven't updated their system recently enough.
Issues like this usually occure either on new builds, or when one building has been split into several flats.