Line Speed Estimates at install and now

[#1]

I can ask those who are interested to check what BT now say that their line estimate speeds are now as to when they had Fibre installed .
Present estimates can be obtained here      https://www.btwholesale.com/includes/adsl/main.html
The reason I ask is that myself and others seem to have had a big drop in the estimates their line can get even though they have had stable higher speeds for along time and that they are starting to drop. This does not help now BT have revised line estimate speeds as we are been informed that we are within the line estimated speeds when enquiring about line speeds with Plusnet.
My estimates are
At install November 2012  55Mbs down  (speed achived was 54Mbs with line IP of 55) Line at this speed until April 2012 when thing started to drop slowly each month
Now BT estimate is 39.9Mbs down (speed achieved is 46Mbs with a line IP of 48.8) still above estimate but for how long?
Same line so why has the speed estimate been downgraded? I've asked a few friends and when checking they have found their estimates have been downgraded substantially.
Thanks to everyone who takes time to post their estimates below.

Bjn

[#2]

BT estimate for my fibre connection:
up to 18.4 mbps down,  up to 3.8 mbps up.
Actual sync speed:
20mbps down,  0.7 mbps up.
I've been in dispute for many months with plusnet / BT about the up stream speed. The estimate hasn't been changed yet but I do have a screen capture just in case

[#3]

BT estimate is  49.7meg down 10.9 up
speed getting now
24.6 down 8.02 up

estimate is still the same

[#4]

The line speed can change, if your speed is well of your estimate then a fault needs raising and we need to push this with our suppliers.
The estimates can change, first they are just an estimate, secondly there will be other things to take into account. The more customers your cabinet  gets the more crosstalk you may see, the estimate is based on the cabinet being 30% utilised so when it goes above this you may then see different to the line estimate. The estimate may then change once there if further factual data available.