The total number of energy complaints has halved since 2014, but customers who make a complaint are less satisfied with how their supplier handles it compared with two years ago, according to Ofgem’s biennial complaints survey.

The suppliers who came out worst in the survey – Npower, Scottish Power and First Utility – recorded the highest ­proportion by far of “very dissatisfied” ­complainants. Even the ­suppliers who fared best – SSE, E.On and EDF Energy – failed to show any significant improvement in overall complaint handling since 2014.