User:JeevesMkII/Halp! Help me choose an electricity and gas supplier

Dear fellow rationalwikians, an unusual request.

Recently, the management company from whom I rent my house sent me a mailer couched as an imperative to move my gas and electricity supplies to Southern Electric. Now, in the security industry we have this maxim which we live and die by: trust, but verify. However, I've been doing it so long I've lost the trust part. I strongly suspect this is an evil plot by them to pick up a commission on every switcher. This angers me.

On the other hand, I have been concerned about my fuel bills of late. In my last electricity bill the price jumped about 50% in the last month. This also does not make me happy. Running the numbers, it seems that Southern Electric would save me about 15 quid a month. Hardly walkin' around money, but not to be sneezed at either. This makes me slightly less angry about the first thing. However, I'm minded to snub the management company by choosing another supplier altogether.

However, since utility companies form a confusopoly it is incredibly difficult to see who has the best deal. They all share the same pricing structure of a gentle gradient to some limit X, then a steeper gradient thereafter as far as I can tell. I strongly suspect that they all choose the gradients such that they can say they are cheapest for some value of X.

However, I want the local optimisation for me. Anyone got the inside track on who is cheapest at the moment, or indeed any recommendation at all?