My Sky Broadband is Sooooo Slow?

Well we got sky broadband a little while ago about 5 or 6 months now, it is unlimited and we are supposed to get 6-7mbps, but instead we get speeds more like 0.88mbps, that was when i done a check at 1:42PM today, I am soooo pissed of becoz we are paying �12 a month for worse than dial-up speeds! my mum will not ring sky and I DO NOT no why. and the stuff I do, online gaming, watching TV online, download A LOT of stuff, I need speed, what can I do to speed up the internet?? the only thing that is not to bad is my ping right now its 156ms. thnx in advance xD