The Scottish Power tariff I was on ended a week ago, so I tried to change to their currently available cheapest tariff. Unfortunately they won't let me do that:
Please be informed that ScottishPower is not offering Online Energy Reward to its existing customers. This service package is only available for the new customers.
This is ridiculous. In order to get their cheapest deal I would need to change supplier twice. They don't even advertise that this isn't available to existing customers. The website just hides it from the list of tariffs if you're viewing the "existing customer" version. (It's also difficult to get from the marketing summary to an actual price list for each tariff; there's no direct link).
Their other options all strangely have £50 penalties for changing tariff or supplier early... perhaps they want to stop people leaving for those suppliers like themselves offering new customers the best prices.
I can find the cheapest suppliers using online comparison websites, but the cheapest option means separating Electricity and Gas so I'd have to deal with two companies who will most likely both give good deals only to new customers and both make arbitrary guesses at future usage so that I end up paying for it all in advance.
Either I repeatedly change supplier every time one or more of them have "new customer only" deals or cease caring about how much it costs and stay with one of them just because it's easier. I've been doing this with Scottish Power for several years now (on whichever tariff appears to be cheapest - this is deceptive because you end up stuck on one while they bring out a cheaper option).
Another option which I've wanted to do for a while is switch to a "Green" Energy tariff. This is easier because the best tariff isn't necessarily the one that has the lowest price. Ecotricity have recently started doing a good progress towards generating 100% of the energy they sell themselves from renewable sources.
Why does it take several weeks to change energy supplier? I can understand that the first 2 weeks are caused by vulnerable people being sold tariffs on commission by rogues, but why is the additional time required?