My sister in law has always been on pre-pay for her gas and electric.
Which is why it's so damn odd that the gas company are threatening to take her to court for a £200 unpaid bill. Because she doesn't get bills, and because she's been in that house for over five years and ALWAYS been on pre-pay. After pointing this out to the company, they apologised profusely, and said that they could see on their computer system that she was on pre-pay.
Then they sent her another bill threatening legal action. Lather, rinse, repeat step one.