Customer complaints about energy firms increased by a quarter last year, according to the Energy Ombudsman. But whether you've had cause to complain about your provider or not, you can save £100s by switching now.

Consumer grievances jumped by 23% to 65,168 in 2015, compared with 52,937 the year before, says the independent adjudicator of disputes between the industry and its customers.

The 65,168 complaints in 2015 is the highest number the Energy Ombudsman has received in one year. There were about 500% more complaints to the adjudicator in 2015 than in 2012, when just 11,283 were made.

(See's How to Complain guide for what to do if you have a gripe with a firm.)

The Energy Ombudsman has revealed that last year billing continued to be the most common problem, accounting for 83% of complaints in 2015. Late and inaccurate domestic bills were ongoing issues.

Customers who had problems switching either suppliers or tariffs accounted for 9% of grievances. However, switching is easy with our Cheap Energy Club – it takes just five minutes to compare tariffs and start a switch. And anyone can do it, whether you're on prepay, direct debit, dual fuel or electricity only. For a full step-by-step guide, see Cheap Gas & Electricity.

'Customers continue to be more vocal'

Chief ombudsman Lewis Shand Smith says: "Energy complaints rose by nearly a quarter over the course of last year as customers continue to be more vocal about their discontent with suppliers."

He adds: "Towards the end of the year, we've seen some suppliers take some encouraging steps, particularly when it comes to improving their billing processes, but there's still more that can be done."

Complaints about energy firms rise by nearly a quarter in a year
Complaints about energy firms rise by nearly a quarter in a year

Which providers received the most complaints?

The Energy Ombudsman will release its annual breakdowns of complaints by firm next month. But in the third quarter of 2015, the body said Scottish Power received the most complaints, totalling 4,554, up 27% from the previous quarter.

Npower came second with complaints rising by 24% to 3,581, while British Gas was third with 1,305 complaints, a 1% fall on the second quarter of last year.

What do these suppliers have to say?

A Scottish Power spokesperson said: “In the Q3 statistics Scottish Power reduced the volume of ombudsman cases received by 27% against the previous quarter, and by nearly 50% since the start of the year.

"Whilst there is still some way to go, our service quality is improving. We want to ensure that our customers experience all of the benefits that our new £200 million IT system will deliver, and there will be no let-up in our efforts to continue our improvements in all areas.”

Meanwhile, an Npower spokesperson says: ‘We’re focusing on improving our overall customer service and we’re already seeing results improve in some key areas.

"For example, total complaints have dropped by nearly 70% compared to last year. We recognise we still have a huge amount of work ahead of us to do and we’re absolutely determined to get it completed as fast as we can."

We asked British Gas to comment, but it refused to do so.

Additional reporting by the Press Association.