Sheriff, call BT and ask them to do a line check, then they have to check the line for faults - it might well be the line that is causing you problems, and if they find a fault then they have to come out and sort it.
From what you have said, the ISP doesn't have an operational problem, so it is down to BT.
Start by getting the voice line checked.
24hours after the problem first materialised and I still have no dsl connection. It returned for a few hours yesterday evening but was painfully slow.
Also, as I use an ISP who rents a BT line I get the classic customer service scenario - ISP says phone BT, BT say speak to ISP!
Brilliant.
Guess I'm stuck with a GPRS connection for an unspecified amount of time then! At least I have a connection though!
Sheriff