Just to clarify from teessides pov.
We ask for your number as we deal with 3 different franchise areas, each with different accounts systems.
If you call from kirklees and say '01484' we dive for SOP, Cable master (2 types) for midlands and Teesside.
If you don't have a ntl number then its ok we just need a post code an house number and we are there. Asking for the phone number is another way of confirming DPA a well.
Account numbers however can be duplicated on the systems so don't help us much.
Hopefully this will all change shortly for the better and we can go back to account numbers as they are more accurate for finding people.
Mark J