SABRA LANE, PRESENTER: United Voice is the union for some of the country's most disadvantaged workers, so you'd expect it would set a high bar for how it treats its own staff, but that's not the case according to more than a dozen past and present United Voice employees who have accused the union of hypocrisy. They've described to 7.30 a workplace ridden with bullying where organisers are put under extreme pressure to recruit new members and while the union demands that other employees negotiate with workers, United Voice staff aren't given a say in their own pay and conditions. Pat McGrath reports.

PAT MCGRATH, REPORTER: They work the longest hours doing the toughest work for the lowest pay in the country's most insecure jobs and they look to one union for support.

UNION MEMBER (United Voice promo video): Without our union movement, we could be facing $5 an hour job.

UNION MEMBER II: We've got to have a united voice.

PAT MCGRATH: But many of United Voice's own current and former staff say this union doesn't practise what it preaches.

TRISTAN, FMR UNITED VOICE ORGANISER: I've seen my friends bullied, I've seen my friends pushed out like I was. And, yeah, I think it's about time that someone said something.

PAT MCGRATH: Tristan, who has asked us not to use his surname for fear of recriminations, is speaking out because he believes the dysfunction at United Voice is damaging the union movement he loves.

TRISTAN: I put in a lot of time and passion into United Voice and into the work I did at United Voice. And, yeah, I didn't feel like I got that respect back from them.

PAT MCGRATH: Tristan cut his teeth working for America's Public Sector Union. United Voice hired him on a 457 visa in 2011. He qualified for the scheme because he'd been trained in a recruitment strategy the union was rolling out.

TRISTAN: The organising model is what it's called. So it really ended up being more of recruitment, just heavy on signing up as many people as you could.

PAT MCGRATH: The model is meant to give members real value for their union dues. But Tristan says United Voice was only interested in numbers and it treated its staff like salespeople.

TRISTAN: We had a target of five sign-ups a week and if you didn't make that, you weren't going to get sacked right away, but if you were consistently not reaching three, four, five sign-ups a week, you would get counselled.

KAY MARCHANT, FMR UNITED VOICE ORGANISER: People were being told that they weren't doing their jobs properly, that they needed to do better than what they were, the reasons they couldn't get sign-ups were excuses, that they needed to push, "You need to push. You need to push."

PAT MCGRATH: Kay was a childcare worker for two decades and a loyal United Voice member before the union hired her as an organiser in 2013. She thought her new job would involve offering support and advice to her former workmates. She was wrong.

KAY MARCHANT: There did come a point where we were told, "You're not to talk to the members about this meeting or that meeting. It's just the sign-ups. It's somebody else's job to talk about those things." I was just there to sign people up.

PAT MCGRATH: It's not just organisers facing extreme pressure in their jobs. We've spoken to 15 past and present United Voice staff who say they've been subjected to the exact type of behaviour the union claims to stand against. One bullying claim and an unfair dismissal claim has been lodged with the Fair Work Commission over the past three years and quietly settled with union cash.

7.30 has obtained the exit interview of one staff member who quit earlier this year. She says she left because her boss' style of management and the mental and physical distress it caused her. And while she was offered grievance procedures, she thought it wasn't worth it because her boss had the backing of union management.

TRISTAN: I can think of several people that were pushed out for being outspoken, who were bullied out.

PAT MCGRATH: Efu Koka believes he's the latest United Voice staffer to be targeted for speaking out. Six weeks ago, he sent an email to the union's national secretary, Jo-anne Schofield, copied to all staff in the country, asking why management has for years refused to negotiate an employment agreement.

EFU KOKA, UNITED VOICE INDUSTRIAL OFFICER: Employees and union officials are not afforded the same opportunity to have a real and meaningful representation in regards to our terms and conditions of employment.

PAT MCGRATH: The union is now taking disciplinary action against Efu Koka. It says his job was already on the line because of serious misconduct and aggressive behaviour and the email was just another act of unprofessionalism.

EFU KOKA: I don't know how that's unprofessional. It's - I suppose it's a tool that we teach our members, our activists. It's called agitation and you - you know, we ask members to send a letter to the boss, the owner, an email, you know, to say, "This isn't right. This is - this shouldn't happen," and I'm just using the same - the same tool.

PAT MCGRATH: Efu Koka says there was a dispute about his personal use of his work phone and he agreed to reimburse the union $80. He says this was long resolved by the time he sent out his all-staff email and was put on notice.

United Voice wouldn't do an interview and didn't respond to our questions, but in the statement says it does have an agreement with its staff. It just wouldn't give us a copy. In reality, the union unilaterally decides how much its staff are paid. It also defended its recruitment targets for its organisers, saying it's common practice within Australia's union movement.

TRISTAN: Recruitment is a very important part of organising 'cause members are strength, but it can't be just recruitment. If you just sign people up, but you don't teach them what it actually means to be a union member, how they can be active in their workplace, then it doesn't - it doesn't really mean anything.

PAT MCGRATH: After two years, it was a practice that Tristan could no longer stomach and after a requesting to go on on unpaid leave for a year and being denied, he had no choice but to walk away from United Voice.

TRISTAN: I work as a builder's labourer. Once I walk out the gate, I don't have to stress out bout it anymore. Yeah, it's a lot less stressful.

SABRA LANE: Pat McGrath reporting.