WORCESTER-BASED energy giant Npower again received more complaints than any other power supplier in the first three months of this year.

The company received 83 complaints per 1,000 customers between January and March – 44 per cent more than its nearest rival.

The firm – which has 5.9 million customers throughout the UK – has topped polls of complaint figures since the end of 2012, with common gripes including bills arriving late, direct debits being cancelled without warning and new accounts not being set up.

Figures released today by consumer group Which? showed a total of 1.7 million complaints were made to the ‘Big Six’ energy companies – Npower, Scottish Power, SSE, British Gas and Eon – between January and March this year, up 15 per cent from 1.48 million in the same period last year.

EDF received the second greatest number of complaints at 46 per 1,000 customers – down from 77 this time last year.

SSE, British Gas and Eon all received about 30 complaints per 1,000 customers, with SSE’s figures doubling from 13 at the start of 2013 to 27 this year.

Which? executive director Richard Lloyd said customers were being “let down” by “poor service” from energy suppliers.

“This has to change,” he said.

“If they want to improve the low level of consumer trust in the energy market suppliers must up their game now rather than wait for the results of a competition review.”

And energy and climate change secretary Ed Davey said it was “unacceptable” that so many people felt the need to complain to their energy supplier.

"Energy companies need to up their game,” he said. “People are switching suppliers in unprecedented numbers, particularly to small suppliers whose numbers have nearly trebled since 2010."

An Npower spokesman said the increase in complaints was down to problems with the company’s billing system.

“We're now beginning to make progress,” she said.

“We're billing 92 per cent of our customers on time and resolving 88 per cent of complaints received on a daily basis within 24 hours.

“In the past three weeks, we have reduced complaints which we could not resolve within 24 hours by 32 per cent.”