yes...even the great and good need some advice sometime

something funny has been happening to my broadband - it was never the quickest to be honest, but in the last few days it has got really slow. I ran some tests, which told me it was running at approx 280kbps. woiw.
I then go to
www.samknows.com which tells me that i am only guaranteed 512kbps because of my location. this is clearly nonense since up until recently it was running at up to 2meg. Also, when I put in my phone number it goes thru all the potential providers and they also say the maximum speed is 512kbps. Even those providers offering LLU (Sky, O2 etc) say 512KBPS.
it is as if my line/area has been downgraded. The speed I am getting now is frankly unusable - I had a faster connection when I had an ISDN line.
This is a business product too - it costs around 30 quid per month - when I see that berk from BT on the telly blabbing on about offering speeds of up to 50meg, I just want to punch him in the face.