Sorry but this part of the story just sounds a bit BS tbh...
I find it hard to believe it actually happened in the first place - you can't just switch someone's phone off at random, let alone do it to several people as part of a scam - I think your friend is exaggerating - perhpas in embarrassment at falling for someone simply phoning up, pretending to be from BT and merely threatening to cut him/her off
This. I don't believe the line was actually disconnected.