We were with BT for a year and had constant problems like emails getting lost, so I was on to their phone helpline and online support quite a bit. After almost every online conversation and a good proportion of the helpline calls, there would be a call to me from an alleged BT helper (always a scam). I warned BT several times that somehow the scammers knew when I had contacted them and they said they would report it. I was worried that desperate people - and we were becoming desperate - might be fooled into giving personal or security information to the scammers, thinking it was just BT phoning back at last. I couldn't believe they weren't more worried about how the scammers knew when I was actively needing help.
From what sp1953 says, it looks like the scammers have notched it up a gear and - although nowadays most of us know to be suspicious - I fear sooner or later they will be successful with this one.
Oh, and we switched supplier and have had a very peaceful, productive, secure year at a much more reasonable price, despite the fact that BT still own the original line. Don't mean to change the subject but I still don't know how that works. Surely, BT should be cheapest?
But, actually, I would have been happy to keep on paying more (almost double) if BT had worked even half as smoothly.