If you are actually on a Plusnet connection then support there may be able to see it as they keep a copy. But the copy can sometimes fail to be updayed from the original BT one.
There is no other way except through the BT speed test.
It might be worth checking here for VP congestion at your exchange.
I have managed to get a new BT speedtest and have posted the results plus my router stats here
kwikbreaks (knowledge is power)
Tue 17-Mar-09 21:27:24
You appear to have an excellent line. This is 100% an ISP shortcoming IMO.
Reply to my ticket suggests that I: 1.Disable any Antivirus/Firewall/Internet security programs.
2.Clear cache, history, browsing history and cookies.
3.Remove other devices, example - Skybox, RedAlert, any extension cables. Also try swopping microfilters.
4.Move router/modem to main BT socket or if problem still persists, move to Testsocket.
5.Unplug and replug DSL cable - wait for modem/router to establish connection.
which doesn't address thae fact that my speed varies considerably over a short space of time!