NPOWER is the worst energy company when it comes to customer complaints, receiving eight times more negative feedback than its nearest rival firm.

The business came bottom in the list of Big Six suppliers in July to September last year, with 253.1 complaints per 100,000 customers, up 25% on the previous quarter. It compares with EDF Energy, at 74.2, and E.On at 61.8.

SSE recorded the lowest rate of complaints (32.3), followed by Scottish Power (46.2) and British Gas (55.0), according to consumers body Consumer Futures.

Npower has apologised for service issues following the installation of a new billing system.