http://www.timesonline.co.uk/tol/money/consumer_affairs/article6630712.ece

This is all about the Code of Practice for Accurate Billing.

Some people think the Code is about getting off paying for incorrect bills for energy billed more than 12 months previously, but it's not that simple. If a bill includes an estimated reading, if the customer accepts it, then it's a bill. The best practice is always to provide a customer reading when you get a bill or statement with an estimated reading. Often a free call, never more than Local rate. When providing the customer reading in response to estimated bill, state clearly to the supplier that you expect the bill to be re-issued. Since this costs the supplier a pound or two and the customer nothing, it's a no brainer.

The better online billing systems, Scottish Power for example, provide an immediate account balance update when a meter reading is submitted, with a full online bill available within a few days.

No idea what the Energy Omdudsman will make of the case which the article doesn't really explain well. However from a customer perspective it's an "Accurate" billing code, not just a "no billing" code. There is a clear Code obligation on the supplier to read the meter at least once every 2 year and failing that only because access to the premises could not be gained, to ensure that an accurate customer read is obtained. There is also a Code obligation on the supplier to ensure that any estimate is based either on previous consumption for the premises or, failing that, typical consumption for a similar property. Unfortunately the article does not explain whether EDF complied or not.

Always provide a customer read when you get an estimated bill.