Many of those trapped in forced marriages live in fear, convinced they could not rebuild their lives if they left.
But one organisation is helping people survive their experiences - and it's being funded by a suburban coffee shop.
The Freedom Hub Survivor School opened in Sydney in 2014.
It's a place where survivors of slavery are trained, encouraged and prepared for the workforce.
Survivors come from a range of different cultural backgrounds and are recovering from different types of slavery.
Sally Irwin, the owner of the Freedom Hub, says up to 50 people have taken part in the program so far.
"So we mainly have people referred to us that have come through forced labour, they may be in a restaurant or in a cafe or in a nail bar or something, where they've not been paid and forced to work long hours. We get a lot of young women that have been forced and sold into marriage, at 14, 15, years of age, and forced to be a domestic slave or sex slave in their own home. We have definitely had some men come in who have been in the building industry, not paid and of course, every country has sex trafficking as well."
Last year she opened the Freedom Hub Cafe.
100 per cent of the profits from the cafe go towards the school.
There are about 52 volunteers who teach at the school and a philanthropist pays the rent.
"What makes the school different to other schools, as in TAFE - we could send them to TAFE or we could send them to other community courses - but most of the survivors have Post-Traumatic Stress Disorder, they don't understand Australian language or culture sometimes, so we actually tailor our classes to be very practical and very interactive and slow, we really work at their pace, and we'll have small classes of one, two or three survivors at once."
24 year-old Hershey Hilado is a volunteer.
She helps teach social skills, how to dress for job interviews, and do make-up.
"A lot of these women can bounce back, but they think that they're no longer good enough for society, and I don't want them to feel that way."
Ms Hilado knows that feeling all too well.
She was forced into prostitution at the age of 14 by her mother in the Philippines.
But her mother found eventually that no customers wanted her so, at 16, she was sold into a forced marriage.
"You wouldn't expect that your parent, the person that you would expect to protect you from all of these things, would be the one actually doing that to you. It's the feeling of being helpless. I wish that no-one had to go through it, because it's very dark and I did attempt a lot of suicides back then, because I had nowhere to go, I had no family."
On her wedding night, while her husband was sleeping, she escaped.
"I had to run about three kilometres from the house, with nothing when everyone was asleep. But before all of this happened I was raped."
Forced marriage is a crime in Australia, but not yet recognised in many other countries including the Philippines.
Brides are often young; fearful, manipulated, and sometimes feel shame - making it difficult to know exactly how many people are being exploited.
Jennifer Burn, a lawyer who represents Australian survivors, says investigations into forced marriages have spiked.
"Forced Marriage referrals have dominated the total percentage of referrals to the Australian Federal Police, so last year 44 per cent of all referrals were in the area of forced marriage. This is something that really we hadn't anticipated would be such a big problem in Australia."
Mr Burn says slavery - more broadly - is a national problem.
State, federal and non-government agencies offer help, but she wants to see an Anti-Slavery Commissioner to help coordinate responses.
"At the moment there seems to be some fragmentation in response between the commonwealth and the states, and between the identification of particular forms of harm."
Slavery survivor Hershey has come a long way since her life in the Philippines.
After her escape, she was homeless for two years, eventually remarried and moved to Australia, and even started her own business.
Now she's inspired to help others do what she did.
"These women, these survivors don't need pity, they need support. They don't need anyone to look down on them, 'oh you poor thing', we don't need that, what we need is real support, love and care from other people."
