How easy is it to change electricity supplier?

I'd agree with the day/night tariff comments. My bills have reduced dramatically (around 40% cheaper) since I signed up.

I do all dishwashing washing etc. After 10pm or before midday. Not really a bind!

I did go into the comparison site yesterday to check it before I posted. I have just accessed it again using GOOGLE.
If you type in the early part of the address such as 'comparadorofertas' and click on the full address in the list you should find it.
The important point about day and night tariff is that the night time period goes up to midday which is when most of us would use additional devices such as washing machine, vacuum cleaner, dishwasher etc. The night time rate is about half of the day time rate so it is worth changing to this tariff if you can. You do not have to watch the clock, just be aware that it is cheaper in the morning. It is certainly a big help if you use air con through the night in the summer.