Low speed for current IP Profile.

[#1]

Router -
Interface Status Rate
DSL Up 5664 kbps / 448 kbps

BT Speed Test -
Download speedachieved during the test was - 1969 Kbps
For your connection, the acceptable range of speeds is 600-7150 Kbps.
Additional Information:
Your DSL Connection Rate :5664 Kbps(DOWN-STREAM), 448 Kbps(UP-STREAM)
IP Profile for your line is - 4500 Kbps

[#2]

https://portal.plus.net/my.html?action=data_transfer_speed
What is the reported current line speed

[#3]

Estimated line speed:
8Mb (Accurate to within +/- 1Mbit) - Checked on 2011-12-13 07:45:29
Current line speed:
3.5 Mb

[#4]

Although it is too low for your IP profile it isn't sufficiently low to fully explain the speed test result