I'm on the 20mb in the bromley area.
Last night at around 4.50pm I was happily downloading an opensuse iso @ between 1900-2200kbp/s, as soon as it hit 5.01pm it shot down to 650kbp/s and wouldn't budge, no matter what I tried to download.
I phoned India, gave me the old "read off a script" run-around (do you have a router?, do you have any p2p software? and the classic......wait for it..... put your computer into safe mode) she insisted it was a fault, I said no it isn't and hey presto what happens 20mins later it goes back to normal.
Makes you wonder whether they know all along and all they have to do is press a button for it to go back to normal.......mmmmmmmmm