X Factor viewers were overcharged by £200,000 because of an interactive vote mistake, ITV has admitted.
Millions of people voted to crown Leona Lewis this year's winner
A data-inputting error meant 1.3 million red button votes throughout the series were charged 50p instead of 35p.
The broadcaster said those overcharged could apply to get the money back and that it would be making a £200,000 donation to Childline.
ITV's admission follows concerns over votes on the BBC's Saturday Kitchen and Channel 4's Richard and Judy.
The problem came to light during a company audit.
An ITV spokesperson said: "We very much regret that a mistake was made in the red button payment systems during the last series of The X Factor and we apologise to all those viewers affected.
"ITV operates a robust audit system which closely monitors interactive revenues and this system picked up the incorrect pricing at the first available opportunity."
It added: "This was an isolated incident of human error and since this incident ITV has undertaken a thorough review of the operation of its interactive services and systems."
The broadcaster also under-charged viewers who used the red button to vote in a competition to win a luxury holiday.
Votes should have cost £1 but entrants were charged just 35p. ITV is writing off the cost.
Premium phone line regulator Icstis, which is already investigating two other cases connected with TV programmes, has been informed.
It is looking into allegations viewers were encouraged to ring in to the You Say, We Pay segment on Channel 4's Richard and Judy even after all contestants had been chosen.
It is also examining BBC One's Saturday Kitchen over allegations viewers were told they could ring up to appear on a supposedly live show which would be broadcast the following week - despite it being recorded just minutes afterwards.