It may be that the problem isn't your side of the wiring, getting your wiring as good as possible just helps highlight where the problem actually sits.
ADSL relies heavily on line distance and line quality, if your line can't handle it then it does cause problems, I'm less than 1km line distance from exchange but our telephone lines round here are really old and on overhead poles, I'm capped at 10Mb for stability but I know my line could go faster if I wanted to endure drop outs.
It's not Skys fault that BT doesn't worry about line quality and only looks at something if your voice service goes down
