A review of ITV phone-ins has identified a "serious cultural failure" within the company.
Shows including Ant and Dec's Gameshow Marathon and Saturday Night Takeaway were among those involved, an audit of ITV's output has found.
ITV executive chairman Michael Grade described the findings as "horrible" and "inexcusable".
Ant McPartlin said he and co-host Dec Donnelly were "extremely disappointed" their Takeaway show was singled out.
"We'd like to make it clear that we had no idea these problems existed," he continued.
"Ant and I are now reassured that strict measures have been put in place to ensure that these kind of incidents can never happen again," said Donnelly.
Although both he and McPartlin have an executive producer credit on Saturday Night Takeaway, he said they had "no direct involvement in the phone line process".
ITV made £7.8 million from uncounted votes. Mr Grade said the company would reimburse those who were misled - a decision McPartlin said he and Donnelly were "100% behind".
I heard on BFBS radio today that even one prize was given to a relative of a producer of one of the programmes.
I hope everyone rings up and gets their money back but they probably won't as they will hear the old familiar "This call costs £1 per minute".