According to uSwitch.com, the 18.6% increase will see the average bill for iSave v12 customers leap from £1,054 a year to £1,250 a year – a staggering £196 a year higher.

At £1,250 a year these customers will no longer be on a ‘best buy’ and will be paying only £15 a year less on average than if they were on a big six standard direct debit tariff.

Darren Braham, founder and CFO of First Utility, said: “Further to our announcement about these tariff changes on the 23rd April 2013, we remain committed to delivering the best value energy for consumers, evidenced by our Price Promise to guarantee our standard prices remain lower than those of the Big Six combined with a very competitive fixed price tariff.

“However, the network costs, the increasing price of wholesale energy and the social and environmental obligations mandated by the government have meant that we regretfully need to increase our prices.”

Those who are unhappy about the price hike are being urged to shop around for other highly competitive deals available on the market, including fixed price tariffs which allow households to enjoy a competitive price today, coupled with longer-term price protection.

uSwitch.com said some fixed price tariffs do not carry any exit penalties, meaning consumers can have the best of both worlds – they can enjoy price protection, but if prices start to fall and the plan is no longer the best price, leaving the provider will not incur a penalty.

One of the most attractive packages in the current market is the EDF Energy’s Blue + Price Promise February 2015 and npower’s Price Fix September 2016. EDF Energy’s ‘Blue’ expires at the end of February 2015 and costs £1,192 a year. This is £58 a year cheaper than the price First Utility customers will be paying after the hike kicks in, but also protects against any future price increases for the next two winters.

npower’s Price Fix September 2016 offers the longest price protection on the market – the fix expires 30th September, 2016.

However, it costs £1,318 a year, which means that First Utility customers would be paying £68 a year more on average for their energy on this plan, although some may think the premium is OK for the long-term peace of mind it offers.