ITV has offered refunds to viewers after it failed to tell them a TV phone-in quiz was being broadcast after lines had closed.
ITV Play's programmes are now shown on ITV2
ITV Play programmes on the ITV2+1 channel routinely carry an on-screen warning that the shows are not live.
But on 16 March this failed to appear. It is thought hundreds of people are likely to have been affected.
ITV said processes had been reviewed and changes put in place to make sure the situation did not arise again.
The ITV Play channel was shelved in March after premium rate phone-ins on several channels were investigated for unfair practices.
ITV Play's output now goes out on ITV2 and is repeated on ITV2+1.
An ITV spokeman said: "There was an unfortunate human error on 16 March, the first night that ITV2+1 replaced ITV Play on Freeview, resulting in the on-screen message not being included in the ITV2+1 broadcast.
"We apologise for this error and are offering a choice of refunds or charity donations to the small number of viewers affected."
They added that premium rate phone line regulator Icstis had been informed.