This is exactly the problem that I had and the reason why I left SKY as their product is ********
DLM gave me an underwhelming speed both down and up on a rock solid line but when I completed I got statements like "we have tried giving you an extra 1Mb/s but the line is unstable" and they refuse (or cannot) just let the line negotiate its own rate with a target SNR.
It is designed to minimise calls from customers with unstable lines who do not know what they are doing - ADSL for the inexperienced consumer.
I gave up and went to BE - got an extra 6Mb/s. Job done.
Would never dream of going back to SKY!
Ex <n>ildram , been to SKY MAX - 15,225 Download
Now with BE Unlimited - 21,000 Download 1,200 Upload! Never happier!