EON pre-pay electric meters?

[rajp]

I've recently bought a flat which already had a pre-payment electric meter in. I asked to have this changed to a "normal" meterbut they were going tocharge me £50. They assured me that the pre-payment meter didn't cost more to use than normal billing. I'm still in the process of moving so rarely at the flat at the moment yet my electric meter is going down by 35-40p a day. On further investigation I noticed my meter has been set to take a weekly charge of £2.77. What is this? It's not a previous debt as that would be listed on another part of the meter