Keymeters ARE more expensive, I used to work for npower and it is the most expensive way to pay for your electric (monthly direct debit being the cheapest as you usually get a discount)
You can arrange for the meter to be changed for free it shouldn't cost you anything as it is really a "choice" of how you pay for your electric.
Find out EXACTLY what you have to do to get credit on the meter.
In npower's geographic area - the midlands, you would go to a shop, details available from the electricity company, get a new card put some money on it and then put that into the meter. Whatever you do donot use the last person's key even if they leave it for you as you could end up contributing credit towards their debt if they had one.
A new customer card registers you and your money against your account and clears any debt or credit of the previous person.
We moved in to our house in may last year, and used key meters until July this year. We didn't find them TOO bad, it helped us budget bills etc. British Gas removed both meters free of charge and fitted us with normal ones. So far we have only had one bill which was more £ than I was expecting, but I know its the same proce each month so it evens out over the winter months I guess. hth.
Thanks for all the messages. House we bought is out in the sticks so me being disorganized a key meter would lead to some cold dark evenings
Rang old company yesterday they identified who owned the meter rang them and new meter being installed tomorrow pm and key meter being removed (hopefully) All free of charge and they even credit back the money we have put on key!!