The 54-year-old faced rejection for a fourth time after returning to the ITV1 show to reaudition in front of the new judging panel. However, following the broadcast of her latest failed attempt on Sunday night, some viewers complained that Rees should not have been allowed to take to the stage again.
A singing teacher, who became friendly with Rees, has today claimed that she contacted producers asking them not to broadcast the footage, which attracted a handful of complaints to media watchdog Ofcom.
Amanda Roberts said that the show had only wanted "someone to ridicule", adding: "'[Ceri has] been in tears ever since. I think she realises they just wanted her to go back on so they could laugh at her. It's pretty mean really."
"I don't think X Factor would put someone in front of the camera on purpose if they were ill," she said. "I don't think that's something they would do. There's psychologists who test out all the contestants before they go on.
"Also, it does come down to the person's decision, if someone has decided to go on the show and they decide to come back. It's only that one person who can make that decision."
She concluded: "I don't believe for a second X Factor would deliberately put someone through, who wasn't mentally stable."
Flack will present the BT Digital Music awards at London's Roundhouse Theatre on September 29. The X Factor and The Xtra Factor continue this weekend with a Boot Camp double bill on ITV1 and ITV2.
> 'X Factor' Boot Camp: First Look - In Pictures
> 'X Factor' 2011: Reality Bites' Ones to Watch
Watch Ceri's audition below: