I decided to migrate to a LLU operator (O2) as BT (Wholesale) have removed the WBC enablement date on my exchange - it was 19/05/2009.
I am now getting faster speeds on ADSL2+ and only paying half of what I was paying before!
I don't know why your speeds have dropped over time?
Is your exchange congested?
Go to click here to find out.
The VP (virtual path) capacity should be green if everything is okay.