Slow speeds aren't really my area any more .. but I can certainly take a look.
Would you be able to supply some troubleshooting for me please..
I already have your modem details from you PM, but could you run a trace say to bbc.co.uk (no www. please) .. if you could also test you speed here:
Just out of interest what does
http://www.broadbandspeedchecker.co.uk/ give you for your speed.. I know the problems with sites before anyone attacks me

I'm just interested.
Please post here so other can offer advice too ..