I have had BT infinity since it was available in my area (Greenwich Exchange). I was getting 33Mbs solidly since then (1+ years) until the beginning of July when the speed dropped to 10MBs. Then the saga began.
1st engineer - turned up, fiddled with the socket in my house and said there was nothing wrong and that my IP profile needed resetting.
The speed went up to 24MBs for a few days before dropping again.
2nd engineer - turned up and said there was a "wire loose" in the socket.
Speed went up to 36 MBs for a few days before dropping to 18MBs
I called up again and got through to a fellow in India who quizzed me for an hour about my Sky box, my ethernet connection etc etc. He just wouln't "get" that NOTHING HAD CHANGED!!!!!
Eventually I asked to speak to his manager and was told that another engineer would be booked for the 30th of July. I was told that if the fault was found to be in my home I would be liable for a £99 charge. When I finally descended off the ceiling I reluctantly agreed to this...
A few hours later someone else called and told me that "there were lots of issues ongoing at the moment and my engineer call would be cancelled". I was to ring back later in the week to book another call.
So far I haven't had the energy to go through this again and am seriously considering cancelling my contract with BT and refusing to pay the fees on the ground that the service I am getting is not what I was getting until 5 weeks ago.