Question Author
Thanks everyone
I was so fed up with the whole business that I contacted BT yet again - heaven knows what they must think of me - and was advised to plug in the ethernet cable. As if by magic...well, it wasn't the shopkeeper but it was the internet (apologies to anyone reading this under the age of 50). He seemed to be saying that now it's switched on again I can remove the cable, but as long as it's not costing me anything extra(?) I may as well leave it in?