Families spend up to £ ##500 a month more on electricity than they have to . customers in four countries are still on their energy sector 's standard variable tariff . In 2013 the PM voted to force suppliers to put all customers on best deal .
Families paying up to £250 a year more on energy than they have to . Three in four families are still on their energy firm 's standard variable tariff . In 2013 the PM pledged to force suppliers to put all customers on best deal .