Some years ago, Stephen Littlechild developed the concept of an Overall Customer Satisfaction score for suppliers in Great Britain’s retail energy sector (Utilities Policy, vol 73, December 2021).
You can read the article here
The calculations are updated several times a year as Ofgem, Citizens Advice and Which? ratings are updated, and the updates are published in Cornwall Energy’s Energy Spectrum. Updates available are as follows:
2024: 22 January 2024 can be viewed here
Professor Littlechild has also reviewed six years of customer service ratings of energy suppliers. Part 1 can be found here