After it was revealed that there was a “toxic” work environment at Bono’s charity’s (The One Campaign) Johannesburg, South Africa office, where workers were allegedly harassed and humiliated, the singer apologized.

“We are all deeply sorry. I hate bullying, can’t stand it,” Bono reportedly told the Mail. The site also reported that a married female worker said she was pressured to sleep with an elderly Tanzanian politician and when she didn’t, was demoted to receptionist and had her salary slashed.

Last November, employees first came forward with claims of abuse and bullying. The charity aims to decrease poverty and preventable diseases, mainly in Africa.

CEO Gayle Smith admitted that there was an “institutional failure” between 2011 and 2015, adding that abuse included name-calling and forced labor, with one manager said to have forced junior staffers to clean her house. Another staff member complained about a manager who made “sexist and suggestive comments” about her to a government official from a different country and demoted her for not sleeping with the official.

“The overall evidence from our investigation was sufficient for me to conclude that we needed to own an institutional failure and ensure that our organization has in place the systems, policies and practices needed so that this never happens again,” Gayle wrote in a letter.