Thought i'd share something a BT Broadband engineer just told me re the service's broadband speeds.
Essentially, they monitor what you're using and apportion bandwidth accordingly. So if you're a heavy broadband user, you should get decent speeds, while more casual users will be running at lower speeds.
So far so understandable, BUT.... if your usage patterns change - for example you go on holiday for a couple of weeks (so your broadband usage tails off) - the service will adapt.
That means heavy users are likely to come back from holiday to much slower broadband speeds, which will only ramp up to their usual level once the system recognises the higher usage rate and adjusts back to your established profile.
Secondly, it means if you're a BT Broadband customer suddenly ramping up your internet usage - such as adopting a streaming service like LoveFilm or Netflix - it could be worth pushing past any pain barrier of initially slow broadband speeds while the network learns your new heavier rates. You should then get higher speeds...