Water firm Severn Trent has confessed it has given industry regulator Ofwat more false information.
The company says it had misreported statistics about the way it handles complaints from customers and enquiries about bills.
The admission echoes a similar problem revealed last month at Southern Water, which will lead to a fine for Southern
Two former executives of Severn Trent Water are at the centre of a Serious Fraud Office investigation.
The company was ordered last week to hand back £42m to customers after a two-year investigation by regulator Ofwat, prompted by revelations in Financial Mail about the falsification of figures.
Ofwat sets bills based on accounts and reports provided by suppliers and it had given Severn Trent permission to raise prices at a higher rate than was justified based on the false figures
In an interim report into allegations that first surfaced in 2004, Ofwat found incorrect income data and intentionally miscalculated debt figures would have had customers paying £42 ($75m) million more than justified by 2010.
Severn Trent overcharged its customers a total of £14m ($25m) over the 2004-7 period, according to the water company’s own statement.
The company has agreed to reduce price limits and return £42m to its 3
The Serious Fraud Office has begun an investigation into Severn Trent Water.
The office was contacted by water watchdog Ofwat which has been holding its own investigation into the company after allegations from an employee.
The allegations concern fears the water company provided unreliable information, particularly accounting inaccuracies, to Ofwat