......that a number of others locally have problems"
Chinese whispers, or was the source the BT engineer?
I have been fortunate, very rarely dropped and always apologetically reconnected automatically.
I live in the sticks, and had to wait until September '04 before I could use BB.
Stories on this forum suggest that distance from the exchange is a factor, as well as the obvious one - can the exchage cope yet!
Assuming that all the rules about filters and not grossly exceeding maximum recommended length of the RJ11 cable have been checked, then.......
If your friend can find sufferers locally, they have a chance collectively to get it sorted.
I think he would be in difficulties with any ISP at this moment