Want to/need to(?) Switch to avoid hikes

Lachicb

Im with Scottish power for gas and electricity. Im on an online std tariff fixed until Jan 14. Should i switch and lock in to avoid all the hikes?? If so, who to??? I enter all my details on a comparison site but it says im on the cheapest HOWEVER thats based on the standard price being £99 a month yet i get charged £140 a month..... So im obviously using more than they estimate so how do i get a cheaper deal to avoid hikes if im apparently already on the cheapest?? (which im obviously not)