The latest table showing complaints for energy providers shows EDF Energy has increased the number of complaints received by 19%.

At a time when tariffs among the Big Six energy companies are all pretty similar and the only difference between them can be their customer service EDF Energy is the only gas and electricity supplier which had an increase in the complaints received between April and June 2011.

The table was compiled by the watchdog Consumer Focus which found that complaints for the majority of the Big Six energy companies fell over the last three months. Rated in stars npower has moved from two to three stars and moved into fourth in the league table.

EDF Energy however has fallen from two stars to one star as a result of the rises in complaints. Consumer Focus said the number of complaints is likely to be down to the implementation of a new billing system.

An EDF Energy spokesman commented that the company was disappointed with the research and said “We’ve invested over £160m in new customer service systems to allow customers to manage their accounts in the way they have told us they want to. We recognise that while we bed down our new system, some of our customers have found it difficult to reach us via our call centres, and we are really sorry for the inconvenience that this is causing”.

He added, “We are doing all we can to ensure we get through this period as quickly as we can so that customers benefit from the improved service this investment will provide, and we are already seeing call waiting times come down”.

Scottish and Southern Energy still tops the table with a five star rating which has increased from four stars since last year. British Gas and E.ON follow with four stars and Scottish Power joins npower with three stars.

Utility Exchange has reported over the past few months that five of the main energy suppliers have increased their gas and electricity prices. However, EDF Energy is the only one of the Big Six energy providers yet to raise prices.