The money will be divided among the customers, amounting to £8 each, and an additional £1m will go to the regulator's voluntary redress fund.
Ofgem found industry-wide weaknesses in customer service and complaints-handling, with some customers being left on hold for hours.
The energy regulator has required all energy suppliers to improve their standards.
The compensation took place between October and December 2020, during the energy-led cost of living crisis.
E.On Next has since improved its service levels, and the energy price cap will be reduced in July.
LONDON DAILY ARCHIVE
E.On Next to Pay £4m in Compensation to Customers for Unacceptable Call Service Failures
Energy firm E.On Next has been ordered to pay £4m in compensation to its 500,000 customers due to unacceptable call service failures, such as long wait times on hold and dropped calls.
14 June 2023 · 23:11 UTC
