As a new user, I thought I'd share this experience with the community.
A little over four weeks ago my broadband speed dropped from almost 7Mb to less than 1Mb, and even then it had severe error problems, so I reported it as a fault. The speed according to the BT speed checker actually fell to 8kb/s
The next day I found out my neighbour, also on BT broadband, had had the same problem at exactly the same time. He had also reported it.
It took 10 days to get an Openreach engineer out to us. He insisted it was coincidence that we had the same problem, and changed over the pairs to the cabinet saying "Leave it for four hours and it will be OK." It wasn't OK.
BT faults refused to touch it again for 10 days after that, saying it would soon be OK. It wasn't OK.
Meanwhile our neighbour on the other side came back from holiday and found their BT broadband had failed as well. They reported it as a fault.
We and our first neighbours then had BT Openreach out again. By now almost 3 weeks had passed. The new engineers spent a day testing and reported that there was a problem with the line between us and the cabinet, which meant it wouldn't pass a broadband signal. Thay said that as it was OK for telephony it didn't count as faulty, therefore BT wouldn't do anything about it. Ever. Nobody in our small court could have cabled broadband, and we were offered two options only if we wanted Broadband: (1) we could leave BT and go to Vodaphone or 3-mobile to get broadband over the phone network or (2) we could have fibre to the house at additional cost.
We ordered fibre, but then 4 days later a new engineer who had come to investigate the fault on our other neighbour's house, agreed that it might not be coincidence for three houses in a row to have the same problem. He asked for an RF interference check. The next day the RF interference check (using an old medium-wave transistor radio) traced the fault to a neighbour's house where a faulty item of mains-operated equipment was radiating interference into the BT cables. The equipment was switched off, and all 3 of us got our broadband back.
It is all working just fine again, for all of us, and I have now cancelled nmy order for BT Infinity as I don't need it.
So the moral here is, if you have a broadband speed problem and you find out that your neighbour has a problem too, get BT Openreach to chack for RF interference.
Full marks and many thanks to the engineers who finally sorted it. And no marks at all to the engonners who advised my to go to Vodaphone or 3-mobile.
I had a very similar problem which took them 6 months, and about 7 engineers, to trace to RF interference from next door, after whatever it was was switched off my connection has been 500k higher and totally stable.
And a small cheap transistor radio is ideal to trace RF interference.
I have to give full marks to the mods on this forum for perservering with my problem until it was solved.