Router help

[#1]

I have got a fault raised re very poor speeds and have been asked to carry out the http://speedtest.btwholesale.com/ test. Part of this involves reconfiguring the router and changing the log in to:  speedtest@speedtest_domain.
I'm having a senior moment (or week) and can't see how to do it!
My router is a TG582n and I'm running Windows 8
HELP please 

[#2]

Hi reserved,
When you arrive at the speedtest page, towards the bottom of the page, just click the yes radio button and then click BEGIN TEST.
You shouldn't need to re-configure the router, as the test should just start.
At the end of the test, you could run the "Further diagnostics" test by clicking the button, if you wish to.
Hope this is helpful.
Regards,
Brian

[#3]

Thanks Brian, perhaps I didn't explain it too well!
It's after running that test you are asked to re-configure the router & rerun the test.

[#4]

The only way I can find is via the Setup Wizard - there is a link at the bottom of this page http://192.168.1.254/cgi/b/ST/?be=0&l0=1&l1=-1

[#5]

Thanks Jim, I did find that but I'm not absolutely sure if that's what I'm meant to do 
As my speeds are so variable,
Date                  Down TBB Down HTTPx6 Upstream
Sat 07/12/13 15:11 12.92 Mbps 12.09 Mbps 0.76 Mbps
Sat 07/12/13 14:56 13.46 Mbps 13.21 Mbps 0.75 Mbps
Sat 07/12/13 13:03 0.32 Mbps 1.31 Mbps 0.59 Mbps
Sat 07/12/13 12:58 1.34 Mbps 2.04 Mbps 0.73 Mbps
Sat 07/12/13 09:30 7.09 Mbps 11.84 Mbps 0.76 Mbps
I want to be absolutely sure that I'm on the right track.
I have tried ringing Support but every time the wait is in excess of 45 mins
Have added a note to my ticket so hoping someone may ring me evevtually or a rep on here may give some advice on Monday.