Speed reports inconsistent

We recently had broadband installed at our business premises with Chess as our ISP. The speeds we are getting seem very poor but when I test the performance I am getting inconsistent information.

The router gives me the following information:

ADSL Link Downstream Upstream
Connection Speed 8128 kbps 448 kbps
Line Attenuation 32 db 16 db
Noise Margin 10 db 22 db

When I test on BT's Speedtester this says we have a profile of 7100kbps and are getting throughput of 6500kbps I have ran this several times

When I test our speed on speedtest.net the speeds I get are always around 0.5 - 1 Mb/s Down and around 0.15 - 0.2 Mb/s Upload

Can anyone enlighten me on why the two sets of results are so wide apart and what might be causing this? We previously had a fixed 2mbps service on IPStream which seemed quicker than the current service, nothing has changed in relation to hardware setup at our end.

Do the .net results tie in with other experience when using the internet?

BT speedtester can bypass the ISP sometimes, so you may be seeing good raw performance from the BT side, but poor ISP performance. If congestion you would expect 2am to 9am to give better speeds, and then it to get worse as the day goes on.

Poor weather during school holidays may mean more kids online too

We are experiencing poor performance in general, we have an exchange server which seems to be struggling to keep up with the queue of outgoing mail due to the pitifully slow upload rate. Sometimes users are also finding that websites are timing out when loading. Very occasionally I might see speeds of 3meg on a speed test but this is very rare.

It sounds like I need to go to our ISP if you think that the issue might be at their end, I was just a bit baffled as BT was reporting a much faster speed that they might try and suggest the problem is at our end. It seems the line should be able to cope with a much faster speed given the BT results.