British Gas owner Centrica has launched a challenge the way the price cap is calculated. The cap, on standard variable tariffs, is due to take effect on 1 January.

The regulator had planned to use the wholesale price for April to September 2018 to set the cap, but now plans to use February to July. The cap will be revised from April.

Meanwhile, Which? has found that the number of cheap energy deals available in the market has dropped. It found that in June there were 88 different dual-fuel deals costing less than £1,000 a year available. In October, November and December, there were between just eight and 10 deals below £1,000 to choose between. (Although it should be noted that at least eight companies have exited the market during that period.)

Alex Neill, Which? managing director of home products and services, said: ‘The price cap is supposed to help consumers, so it is a real cause for concern that some of the best-value deals seem to have disappeared from the market just as it is introduced.

‘This demonstrates why the cap can only be a temporary fix – what is now needed is real reform to promote competition, innovation and improved customer service in the broken energy market.

‘If you are unhappy with your current energy provider, you should look to switch now to save significant amounts of money. It’s also important to consider other factors, such as customer service.’