i have had similar problem..i was happily downloading at 36mb for 10 month...then two week ago i renew my contract...and my speed has now dropped to 31mb yet my noise margin is perfect at 6db...the only thing i have noticed is my hh5 keeps re booting every 2 days....but...its done that for over a year...and speed used to be a lot higher...something doesnt seem rite..there are loads of us on here complaining about are speeds being worse....coincidence ????
My Hub doesn't even reboot, not had any problems that way, it is very strange.
Accourding to the BT wholesale website I'm not only getting 18 Mbps.
In fact it says there is a problem, ticket has now been opened so hopefully wil get a reason.