Ofgem has refused to publish an investigation that found “severe” issues with the way energy companies treat customers in debt.

The energy market regulator announced today it had found problems with the way that 16 suppliers treat customers facing financial difficulties, including “severe” issues at three companies and “moderate weaknesses” at a further five. Eight of the firms had “minor weaknesses”, including three of the UK’s biggest suppliers, EDF, E.ON and OVO.

But the regulator would not publish its findings in full, say how many people in debt had been mistreated, or what the consequences had been for those people.

It offered only generalised examples of some of the failings it identified. When asked by openDemocracy to share a breakdown of what issues were found at each supplier, Ofgem refused.

Ruth London, a founding member of Fuel Poverty Action, told openDemocracy: “It is beyond outrageous that on top of the horrendous price rises we are all facing, people have to deal with suppliers’ refusal to even fulfil their customer service obligations.”

Ofgem suggested minor issues – observed at Ecotricity, EDF, E.ON, Octopus, OVO, Shell, SO Energy and Utility Warehouse – could include failing to take into account all relevant factors about customers when setting debt repayment plans.

The moderate weaknesses identified at five suppliers – Bulb, E Gas & Electricity, Good Energy, Green Energy UK and Outfox the Market – could lead to customers being denied necessary support and not offered flexible repayment arrangements when in debt.

Three suppliers – ScottishPower, TruEnergy and Utilita Energy – were found to be putting customers “at a serious risk of poor and potentially serious outcomes” as they “did not have a consistent and structured approach to managing customers in payment difficulty or [there was] a risk that policies designed to support customers were not being implemented”.

Ofgem would not give further details of its findings.

It comes as the energy regulator faces criticism from MPs and campaigners for having not been tough enough on energy suppliers in the past. In August, one of Ofgem’s board members resigned, saying the regulator had given “too much benefit to companies at the expense of consumers”. 

Ofgem said it was engaging with all 16 suppliers and had served immediate enforcement notices against two, ScottishPower and Utilita Energy, which require them to make immediate improvements and could lead to financial penalties.   

In its enforcement notice to ScottishPower, the regulator said the company’s staff “appear to be failing to follow their own internal policy and procedures on setting lower repayment amounts where the customer is in payment difficulty”.

Utilita was ordered to “cease the use of call scripts which tells [sic] customers that additional support credit is not a licence requirement”. Suppliers are obliged to give loans to customers with prepayment energy meters who are in vulnerable circumstances and have exhausted other options.

British Gas was the only supplier that Ofgem found to have no significant issues.

Jonathan Brearley, chief executive of Ofgem, said: “We have reviewed suppliers on how they help customers who are having trouble paying their bills, particularly those who are vulnerable, and found some suppliers have fallen short of the standards Ofgem expects.

“We accept that there are many pressures on energy companies in the market this winter, but the needs of vulnerable customers must be part of their top priorities. We will now work with companies on where they can improve.”