The producers of An Open Secret, a controversial documentary about child sex abuse in Hollywood, have criticised their director, Amy Berg, for failing to sufficiently promote it.

Executive producer Gabe Hoffman, who bankrolled early screenings of the film with his own money, complained to industry magazine Deadline that, while Berg had granted some print interviews, she had turned down “dozens” of requests from broadcast news networks.

“It’s heartbreaking,” he said. “It’s been a disappointment to everybody. To be given a national platform to support an independent film is like a winning lottery ticket – a real chance to talk about the issues and raise awareness and to do some good. But Amy has declined all these press interviews, citing a busy schedule.”

An Open Secret, which airs the testimonies of a number of men who say they were sexually abused by Hollywood film-makers as children, was released on 5 June and had a limited run in the US, charting the lowest grossing box-office figure distributor Rocky Mountain Pictures had seen in 26 years.

“We knew it would be challenging subject matter,” Rocky Mountain executive Ron Rodgers told Deadline in June. “[But] I don’t think we’ve had any interference from Hollywood and I don’t jump onto conspiracy theories”.

Berg has not commented on Hoffman’s remarks, but sources close to her who spoke to Deadline say she warned An Open Secret’s producers that their decision to bring forward the film’s release date would conflict with her schedule. She is currently working on a documentary about Janis Joplin and promoting her film Prophet’s Prey, about Warren Jeffs, the former leader of a fundamentalist church sect who is serving a life sentence for sexual assault on children.

The director’s previous work includes Deliver Us From Evil, her Oscar-nominated debut about the Irish Catholic priest Oliver O’Grady, who served seven years in prison in the US for child molestation, before being deported back to Ireland. The film shows O’Grady admitting to molesting and raping multiple young victims during his time in America.

An Open Secret has had a tough time gaining traction, despite receiving lots of press from print publications, like the Guardian. It was given an R rating by US certification body the Motion Picture Association of America (MPAA). Many cinemas refuse to show R-rated films and they tend to struggle at the box office. Hoffman wrote an open letter to the MPAA’s chairman Christopher Dodd, asking for the ratings body to reconsider their decision.

“We were extremely disappointed to find our film – which discusses these issues maturely and carefully – thrown into the same category as films which display gratuitous sex and violence,” he wrote.

“If just one single teen … finds their inner strength, and is able to escape their current abuse situation because of your decision, wouldn’t that make your time spent personally reviewing the film, and its rating, all worthwhile?”