Would changing isp help?
The sky broadband connect pacakge, the £17 a month one, is provided over the BT network (to exchanges where sky dont have their own equipment installed in the exchange e.g. small villages with less than 9000 customers), That network becomes congested everynight usually and the only thing sky really care about (on the £17 a month package anyway) is web browsing, email, VOIP (skype etc) and programmes like windows live messenger etc, So on the connect package they have p2p, ftp, and online gaming on a lower priority than web browsing etc, But when it becomes so congested even the things with number 1 priority (web browsing) will start to suffer, So its basiclly everyone using the same BT equipment at the same time (wether or not their using sky, BT, o2, Orange or any other provider, all providers using BT will suffer this) are all competing for speed. So basicly yes the sky access package is oversubscribed (as all packages are anyway) you will have to change providers to recieve a better
