The gap between how well the best and worst performing energy suppliers are at dealing with customer complaints is the widest on record, Citizens Advice reports.

Extra Energy performed 80 times worse than the best performing supplier SSE, according to the charity’s latest energy complaints league table.

Citizens Advice publishes the quarterly results to show customers how well energy suppliers are dealing with complaints. Suppliers’ scores are calculated based on the seriousness of the complaint against them and how long it took to resolve. Firms with lower complaints ratios are better at resolving complaints than those with high scores.

Citizens Advice’s latest table of the 21 largest energy firms in Great Britain, for April to June 2016, shows:

  • Extra Energy remains at bottom of the table for second quarter in a row  - recording highest ever complaint ratio of 1791.2 per 100,000 customers, according to our scoring system, compared to 1,682.0 per 100,000 customers the previous quarter.

  • SSE retains top spot with an even better performance - getting a complaints ratio of 22.5 per 100,000 customers, compared to 28.4 per 100,000 the previous quarter.

  • Last quarter’s second best performer Flow Energy drops to tenth place, with a fourfold increase in its complaints ratio compared to the previous three months.

  • Npower’s complaints ratio drops by over a third - however its rank remains unchanged as a new supplier enters the table in a higher position.

  • Newcomer GB Energy secures 9th place with a complaints ratio of 125.4 per 100,000 customers.

  • Utilita more than halves its complaints ratio, while Ecotricity has doubled its complaints ratio compared to last quarter.

The latest data shows many energy suppliers’ performances fluctuating on the previous quarter - with a few significantly improving their complaints handling and others getting worse.  

Meanwhile, the difference between the complaint handling scores of top of the table SSE and bottom place Extra Energy respectively is at its widest since the table began five years ago.

Common problems that people reported to Citizens Advice about Extra Energy included late or inaccurate bills and difficulty getting through to its customer service team on the phone when they had an issue to resolve.

Gillian Guy, chief executive of Citizens Advice, said:

“People shouldn’t face a gamble on getting good customer service.

“The latest league table shows some suppliers are getting much better at sorting out their customers’ problems, but it's disappointing to see others getting worse at dealing with complaints.

“Patchy and unpredictable customer service affects people in many ways - from the financial stress of being hit with a late bill, to the time wasted trying to get hold of a supplier on the phone.

“All suppliers must step up their efforts to make sure they are delivering a consistently high standard for their customers.”