Thank you for link - I will certainly check it out.
BT have now "Closed" my fault fix (third time they've done this) and are opening a new one, the symptoms are exactly the same as they were on March 1st. What intrigues me is I can't get further than BT Support - latest one was very pleasant and promised to ring me between 14.00-16.00 yesterday once checks were made (didn't) - I was not surprised. Messages have been passed on (I was told) to the next level and they'd get in touch - didn't.
No need to respond to the above ramblings by the way, after three weeks I've accepted this Kafkaesque scenario...
Is the phone line always noisy if it is then you need to report a noisy phone line to BT faults on 151 with NO mention of broadband in the call once line noise is resolved then your broadband will recover automatically