Well well, the engineer turned up today and what a suprise: it appears not to be a line fault, but a problem with the account!
He (engineer) was a very nice man, and was apologetic for not being able to do more! And here was why he was unable to: he tried phoning - from my phone, therefore no line fault - to one of the **experts** in the exchange I believe, but guess what? That's right they don't work bank holidays!
I mean whats the flippin' point in having field engineers out and about, but any essential support staff they may require not being there!
In essence the engineer diagnosis was that maybe they have switched my account off in error - it better bloody well be in error!
Of course if it was an account issue all along, could the initial call to 151 have not picked up on that?
Will try phoning 151 again! Or maybe I should just phone BT