Interim update, and thanks FL310.
The new USB ISDN TA seemed better for a while. Then the nuisance disconnects began again. But only for a day or two and then the whole caboodle crashed royally and BT are digging up the road as I write. I'm in a reversionary mode to write this using free minutes on my mobile 'phone.
Still room for cautious optimism (anyone got a cure for optimism?) as BT is now completly replacing the underground cable which had as much water in it as it had wiggly amps.
Don't miss the next exciting instalment.