Late last year, David Cameron's response to Labour's energy price freeze was to announce a headline £50 reduction in bills, by cutting energy efficiency programmes.

Of course, it wasn't a £50 saving as bills had already gone up by £110, meaning an at-best average £60 price increase. That didn't stop the Prime Minister claiming to have cut bills, with hapless Liberal Democrat Energy Secretary Ed Davey declaring it was the customer who was victor. The SNP, whose own theoretical policy is an imitation of the Tory model, should take note.

Far from saving every customer £50, it turns out that an estimated 3.7 million billpayers on fixed tariffs have missed out on £140 million of savings; or, £38 of the headline £50 they thought they were being given is, instead, being held on to by four of the six large suppliers. By cutting and spreading even thinner the stuttering ECO programme of energy efficiency, it is those who can afford it the least who are finding schemes to make their homes warmer are being cancelled.

At the same time, those who have heeded the Government's price rise message to switch supplier and take on fixed-price deals are paying more by missing out on the reduction they had been promised. The real winners are, again, large suppliers who lobby furiously to have obligations taken off bills and then, rather than pass that saving on, keep the additional margin for themselves.

At the time, I and others warned that it would be at the discretion of the energy companies to pass through this reduction to the consumer. Yesterday's confirmation that most large suppliers were treating it instead as a bonus for their failing balance sheets was instructive.

While every big supplier spends PR money claiming they are sorry for their excesses of the past, keen to help customers with costs and determined to restore trust, the reality is that, in this instance, for four out of six companies old habits die hard.

And so the case for real reform is made even more compelling. One of the curiosities of the scrutiny of energy pricing is the way in which the Nationalists have all but ignored it.

When put under pressure, the SNP's energy spokesman in Holyrood regurgitates previously discredited claims of blackouts and their deputy leader announced a remarkably similar policy to the Tories.

Freedom of information requests show that, when Alex Salmond meets the big six, he doesn't tackle them on prices and profits. Like the UK Coalition, the SNP seem content to accept rather than challenge the market dominance which has led to repeated bad practice.

With 95% of the domestic consumer market between them and a series of scandals relating to doorstep selling, predatory pricing and holding on to overpayments, the latest revelation makes it clear that the large suppliers are finding it hard to live up to the reality of their newly found rhetoric of the responsible.

That is why there is urgency in the need for reform to the wholesale and retail energy market to make it clear, fair and transparent.

There is urgency, too, in the need for a regulator that properly challenges market dominance and promotes competition in the customer interest. And there is urgency in the need to give households and businesses the ability to understand why they are paying what they are paying.

Labour's package of reforms is intended to bring that clarity. The ringfencing between supply and generation arms of the big companies to prevent collusion; mandatory open trading of power to stop secret deals that can keep prices artificially high; a regulator acting in the interests of the consumer with powers to challenge the big companies; and a focus on long-term decisions to ensure security of supply are all part of the picture.

Without these fundamental changes, distrust in energy suppliers will continue. We have seen this week, yet again, that they are unable to help themselves. It is time for less timidity and more focus to make the energy market fit for the long term.