Complaints to the Energy Ombudsman reached a record level, passing 100,000 last year - with investigators ruling against suppliers in three-quarters of cases.
The figures come amidst growing anger at the pre-payment meter scandal, with harrowing accounts unearthed of vulnerable people's homes being broken into by British Gas subcontractors.
Incorrect billing, poor customer service, and problems switching suppliers were the main issues prompting complaints, the BBC reports.
