This is the best site for testing your speed. Make sure you have ALL other applications closed to get a true picture.
http://www.thinkbroadband.com/speedtest
There are 3 main points to consider -
MSR - this is your maximum stable rate - you would normally get about 0.5mb under this
CLR - your current line rate (look at the download speed on the test)
FTR - this is the fault threshold rate - this is the lowest speed that BT would accept on the line - if your speed is constantly below this then it would need to go to wholesale to be reset/repaired
Without any testing systems I couldn't tell you what you should get but the BT THD can if you ask them!
NEIL - SPACED is asking about slower speeds on the line - 1.5mb was his previous avg speed but he has now fallen well below this.
The THD guy should've gone through basic internal/PC diagnostics first then, if required send it off to the wholesale team for network diagnostics - you just need to wait for them I'm afraid!
Let me know how it goes
A xXx