Chris
Yes - at last my internet is working, please see my ticket.
The BT engineer and another chap at BTw were very helpful and spent 3 hours getting things back on track for which i'm very grateful.
BTw did a "rebuild of my profile" (I think) which appeared to be the main problem; following this there still seemed to be a problem which turned out to be the test router PN sent and my Linsksy!; tried two other routers which worked fine.
Currently I'm using my ancient none-wireless US Robotics router - 16v, using a 12v power plug because I can't find the one that came with it.
Connection has dropped a couple of times since the engineer left, I have to reboot the router to get it back. I'm really hoping this will settle down.
Chuffed to bits to be back online, but still very very peeved that it took 3 weeks!