Hi Anne
Don't know if this helps but we had a very similar problem last year (bad weather related) we are with xln adsl broadband at work and last year the broadband would run around 1-2Mbps it sometimes dropped out completely during the wet and windy weather, we had the usual conversation with their tec guys, you know, plug the router into the master socket bla bla bla, the fault must be your end, have you reset the router etc, etc, in the end I requested a BT engineer, he checked everything in the office and found nothing wrong, so he went to the cabinet in the street, came back about 30 minutes later and said I found the fault.
The fault he found was the wires had been striped back too far and were exposing copper wire, he said condensation in the cabinet was causing an arch.
I did not believe this would cause such bad broadband speed but we have not had the same problem since he fixed the exposed copper wires and our speed as been around 6-7Mbps.
