TV host Richard Madeley has said he and wife Judy Finnegan are "livid" about problems with the You Say, We Pay quiz on their Channel 4 show.
The quiz has been suspended until Channel 4 has investigated
It follows claims that callers were told to phone a premium rate number even after contestants had been chosen.
Speaking to the Daily Mirror Madeley said: "I think it is a cock-up, not a conspiracy. We're angry on behalf of our viewers."
Channel 4 said it plans to refund the callers or donate the money to charity.
A freephone hotline has been set up for anyone who believes they were not correctly entered into the competition.
Channel 4 has promised to donate any cash profit they may have made during the competition to Great Ormond Street Hospital.
Premium rate phone regulator Icstis has also launched an investigation.
Icstis said it would look into the matter as quickly as possible, owing to the "big public interest" in the allegations.
The presenters claim they were unaware of the issue surrounding the quiz, which has been suspended until the investigation is complete.
Speaking on the show, Finnegan said: "Many of you will have read over the weekend and today that some problems have come to light with the You Say We Pay competition.
"It seems some callers have not been properly entered into the competition."
Madeley continued: "A full investigation has been launched to find out exactly what's happened, and we won't be running You Say We Pay for the time being. "
Finnegan added: "Richard and I knew nothing about this until late on Friday afternoon - we were very shocked and also angry on your behalf. We're very sorry."
It is being reported this scandal could cost Channel 4 thousands.
A spokesman for the broadcaster said: "We cannot confirm any figures and we would caution against extrapolating them because the number of calls varies significantly from week to week."
However the network has admitted the problem affects the current and last series of the show.
The Mail on Sunday claimed leaked emails showed that the quiz's premium rate entry line continued to be promoted after a contestant had been selected.
Icstis spokesman Rob Dwight said the regulator would ask to view the evidence that led to the Mail on Sunday article.
It will also talk to Channel 4, production company Cactus TV and Eckoh, the provider of the £1-a-time phone service.
"As a consumer protection body, we have a duty to investigate all complaints, so that is what we will be doing," Mr Dwight said.
The Mail on Sunday claimed it had obtained a copy of a message sent by Eckoh to Cactus TV timed at 1709 GMT last Wednesday, listing 24 names and numbers.
But ten minutes later the programme again invited callers to try their luck on the quiz, the report said.