You'd think it was a joke, or a scam and I bet you wouldn't be very willing to pay.

Energy is a commodity, just the same as Tesco's finest, so why do power companies think they can get away with, effectively, putting up the agreed price of electricity AFTER you've used it.

Sounds unbelievable, but it's true, according to correspondent Steve Mackinder, who writes:

I received a letter from EON on September 7 advising me that they had increased my electricity charges on August 22 without giving me any notice that they intended to do this and thereby giving me the chance to switch to other suppliers. Is this legal or morally acceptable?

Obviously I've used the electricity but it seems wrong to me. Could Tesco write to me and retrospectively demand more money on last month's shopping? I doubt it!

This is a serious point and I'd be grateful for your thoughts as I know thousands of people will be in the same dilemma. I accept that charges will rise but "stealing" money retrospectively without giving the consumer a chance to switch to another supplier, or moderate useage if you are on a low income, must contravene our basic consumer rights. I guess anyone in our area using EON will have had a similar letter.

Steve Mackinder,

63 Sluice Road, Denver

I put Mr Mackinder's points to e-on (or E.ON, even they can't decide) press officer Jonathan Smith, who responded initially by saying it was not true. The announcement made on August 21 was that the price rise would be in operation from the next day, August 22, so it wasn't a retrospective price increase.

How was it announced? By press release.

OK, he accepted that if the media had not used the press release, or Mr Mackinder missed it in the newspapers or on TV and radio then his letter from e.on on September 7 may well have been the first time he had been notified.

I queried why it had taken from August 21 (and presumably the announcement could have been made before that, if e-on bosses had not decided on that very day to increase the price – one assumes these things are a little time in the planning) until September 7 for a letter to arrive.

"We have 5.5 million customers and these things take time," said Mr Smith.

He accepted that customers were at liberty to seek a cheaper supplier if they were not happy with the price rise. I pointed out that even if customers had been aware from August 21 that the price was going up the next day they would have to pay the increase for the time it took to switch supplier, which could not be done overnight.

Mr Smith responded that they would, in that case, only have to pay the increase for as long as it took to switch supplier, which might not be too long.

He did not like the Tesco analogy, pointing out that you could not complain if the coffee you were going to buy from Tesco today was more expensive than the coffee you bought a month ago.

No, I said, but you didn't have to buy it. You could turn on your heels and maybe buy it cheaper at Sainsbury's. Which was not the case with an overnight increase in electricity prices.

Well, it's what we do and all energy suppliers do it and it's not illegal and it's not our fault, it's the increases in wholesale prices, finished Mr Smith, who then very kindly emailed me the e.on press release dated Thursday, August 21...

Press Release

Thursday 21 August 2008

E.ON announces price rise for residential customers

• Electricity prices to rise by 16%, gas prices by 26%

• Over a quarter of customers unaffected

• Spend to assist most vulnerable customers doubled

• Prepayment meter customers to pay same price as E.ON standard prices

E.ON has today (THURSDAY) become the latest energy supplier to respond to rising wholesale energy costs by increasing electricity and gas prices for the majority of its residential customers, effective from 22 August 2008.

Prices will rise by 16% for electricity and 26% for gas. The move comes as a direct result of rising wholesale costs which have increased by over 51% since February 1...

Graham Bartlett, Managing Director of E.ON's Retail business, said: "I'm very aware of the effect that today's announcement will have on our customers..."

It seems unfair for an industry which makes so much profit, and sells a surefire commodity which we all have to buy, to charge its customers in retrospect. For, despite all Mr Smith from e.on has to say, that is the effect of overnight increases in fuel charges.

It seems wrong that the industry should behave in such a cavalier fashion towards its customers.

And it seems pitiful that it cannot organise itself to give its customers prior notice of price increases when it is clear they do not have the option of immediately shopping elsewhere.

I don't have enough information to truly agree we live in rip-off Britain, but responses such as these do nothing to dispel that "stand and deliver" feeling I sometimes get when it comes to energy and fuel costs.