Finally an OR SFI engineer called me, came to the house and checked everything, line check OK but no broadband! What a surprise. Went to street cabinet and found a component failure, connected me to another port and all sorted. Took 1 hour after 7 weeks waiting. Thanks for all your interest. The lesson? It seems that OR were testing the connection from the exchange and it was registering OK, BT were also testing line and seemed OK, they never contacted me to ask if it was fixed. SFI said the fault would have been flagged up to him after 28 days but because BT had erroneously cancelled the original fault report after 3 weeks this period was not factored in. All seems very much like a serious communications shortcoming which will in detail be referred to OfCom.