FTTC D/L speed back to ADSL speed

[#1]

Hi all,
All of a sudden a day or two ago, my download speed (which is usually around the 72/73mb mark), has dropped to around 8mb (my upload speed retains it 'fibre' speed of around 17/18mb).
Does anyone have any idea as to what this could be?!
Interestingly, the page that details my plusnet 'current line speed' and 'estimated line speed' have changed and I'm getting an error running the btspeedtester when running further diagnostics... (see the attached).
Any help much appreciated as always!
Chris

[#2]

Hi beepitybeepbeep,
Apologies for any inconvenience caused. We've had a look for you and it seems the profile on your account was set incorrectly. We've amended this now so you should see an increase in speeds in the next 10-15 minutes.

[#3]

Hi Linn,
Profile back up to 78mb - thanks.
How come the profile on my account suddenly got re-set to something completely different?
Cheers!

[#4]

Couldn't find a reason at all for it