Problems with line speed

[#1]

Recently logged a call with PlusNet as speed had dropped to less than 128kbps. After investigation PN says fault has now been fixed but I still have to wait for 72 hours before my line speed will increase to the normal 4+ megs.
Apparently this wait for 72 hours is enforced at the local BT exchange by their equipment, line is monitored for 72 'clean' hours before the speed is ramped up again.
I find this hard to believe and have never come across this with any other ISP broadband fault. Can anyone shed some light on this.
How could business work if they had to wait for 72 hours after every broadband fault was fixed?

[#2]

You will come across it at every ISP that uses BT IPStream I'm afraid.
It's how the product was designed.  In reality though, it should be more like 24 hours for the profile to pick back up again if you're now getting considerably higher sync speeds.

[#3]

Someone should have mentioned you need to resync (ideally in daylight hours, if you haven't already) for your sync speed to pick up before your profile will change.