Energy regulator Ofgem is “taking action” against all 11 of the UK’s biggest suppliers for failings in how they deal with customer complaints.
In its complaint handling survey, the regulator said it had “compliance cases” open against four companies over customer dissatisfaction with how they handled complaints.
It has also asked another seven to improve their procedures.
When Ofgem last carried out the survey in 2016 only two firms were named.
Ofgem has opened compliance cases into First Utility, Ovo Energy and Utilita over their poor handling of customer complaints.
It has also expanded a customer service case against ScottishPower to include how they handled complaints.
Ofgem has also required all the other domestic suppliers included in its survey – British Gas, Npower, Utility Warehouse, SSE, EDF Energy, E.On and Co-operative Energy – to come up with plans to improve how they deal with complaints.
Dermot Nolan, chief executive of Ofgem, said: “Although the level of satisfaction about complaint handling has increased over the past two years, it is still unacceptably low.
“Some suppliers need to be doing considerably more to get the basics right and provide a service their customers deserve.”