A record 1.7m complaints were lodged against the Big Six energy suppliers in the first half of the year, according to new figures.
Most of the grievances, up 15pc on the same period last year, are due to innacurate charges after companies estimated customers’ electricity and gas usage instead of relying on meter readings.
Npower faced the most complaints, according to the figures produced by Which?, with an average of just over 83 objections per 1,000 customers – a rise of 70pc year-on-year.
This was mainly due to the company switching to a new billing system last year that resulted in some customers’ direct debits being cancelled and others receiving no bill at all.
Among the rest of the Big Six, EDF recorded 46 complaints per 1,000 customers, E.on 33, British Gas 31, SSE 28 and Scottish Power 14.