Different Speeds

I have complained to BT that my speed has dropped from 800kbps to 120kbps. The result of the BT Speedtester is shown below:

Download speed achieved during the test was - 91 Kbps
For your connection, the acceptable range of speeds is 50-250 Kbps.
Additional Information:
Your DSL Connection Rate :736 Kbps(DOWN-STREAM), 448 Kbps(UP-STREAM)
IP Profile for your line is - 135 Kbps

This is even worse.The BT Broadband engineer tested the line and gave me the Downstream speed which of course looks OK fo ra rural area - but seems to have no bearing whatsoever on the actual download speed ! The engineer said he could not do anything as the speed shown 736kbps is acceptable.
What do I do now ? Lousy speed and BT saying that it is 'acceptable' to drop to 10% of the original speed. Can someone also explain the variance in speeds please -in ordinary english if possible.

Best thing is to post your Line stats: http://www.kitz.co.uk/adsl/frogstats.php

and your Exchange: http://www.samknows.com/broadband/exchange_search

See this page about the IP Profile system. Yours should recover soon to 500, giving you a download speed of more like 400kbps than 120. But if you are used to 800, then we could do with seeing the information BatBoy requested, to see what else is wrong.

Hi Preseli

If you send me over your details via http://bt.custhelp.com/app/contact_email/c/4950 I will run some tests on your broadband service to see if there are any potential issues that may be causing this.

Regards David