A water company has been named the industry's worst performer for customer complaints for the sixth successive year, despite responding positively to pressure from the Consumer Council for Water (CCWater).
Southern Water had more than a 20 per cent reduction in written complaints in 2017/18, but still failed to improve its relative position in the Water Watchdog's annual complaints report.
It remains bottom of 21 companies in England and Wales for complaints and for the number of telephone calls it received from customers wanting to resolve problems - known as 'unwanted contacts'.
Sir Tony Redmond, London and South East Chair for CCWater, said: "There are signs the company is heading in the right direction but we have not seen enough progress.
"There will be no let-up in the pressure from us until the company gets more into line with the rest of the industry."
Southern Water will remain on CCWater's 'watch list' for the third successive year with the company having to provide the watchdog with quarterly reports on the progress it is making to reduce complaints.
Across England and Wales consumers had to make more than 2.1 million telephone calls to resolve problems last year, with nine out of 21 water companies reporting an increase. Four companies also reported an increase in written complaints from their customers, although the number to the industry as a whole fell.
Fewer household customers had to turn to CCWater for help resolving a dispute in 2017/18, with the watchdog handling 6,815 complaints from household customers - down 13 per cent. The watchdog helped to return almost £1.4 million in financial redress to customers.