The two young Frenchmen were so malnourished they had wounds that would not heal. They were sharing slices of cheap bread because they had no money. They had come to Queensland on the promise of work.

Because they had been paying the backpacker hostel for bunks while they waited for work that never came, they were sinking into debt. Now they were sleeping in a tent in a park with no way out and nowhere to go.

It is a story Kate Polsoni, formerly a resident of Caboolture in south-east Queensland, has heard time and time again: vulnerable young people, a long way from home, far from everything that is familiar, running out of money, ripped off. In the past 10 years, Polsoni and her husband took hundreds of backpackers into their home and fed them until they were back on their feet. In one year alone, 136 foreign kids in serious trouble came through their house. Polsoni now operates a drop-in community centre in Collarenebri, in outback New South Wales.

It is supposed to be the great adventure – being young and free and seeing the world. But in Australia there can be a dark side: backpackers exploited, and at risk. “There is so much abuse and extortion, it is becoming an epidemic,” Polsoni says. “Backpackers have got no government or authorised body that can stand up for them.”

In fact, it is happening under the auspices of the Australian government. The “88 days” work scheme allows young travellers to extend their visas for a second year if they successfully complete three months’ work in a regional place, fruit picking or other labouring on farms. Billed as a cultural exchange, in reality it is providing cheap labour to the agricultural industry. Backpackers and migrants provide two-thirds of the agricultural workforce. Performing largely unregulated work, they can be paid well below minimum wages – modern slavery, often in remote places without phone or internet connections.

Farm work hostels co-ordinate with farmers to provide jobs, but when backpackers arrive they can find themselves slugged for a bond and rent in advance and then spend weeks sitting around waiting for work.

“So they don’t want to leave because they have paid this money,” Rosie Ayliffe, a former English teacher, says. “When the work does come around, they give them one or two days at a time. They want to keep them there as long as possible paying rent. They pay in excess of $200 per bed, per dorm $800 a month, with eight to 12 people in a room. Some of them are absolutely disgusting.” The enterprise is highly profitable and “a con”.

Polsoni first became involved when she was no longer able to work as a nurse and had instead found a job as a sales manager in a call centre employing backpackers on the Sunshine Coast. Not wanting girls to walk home at night, she drove several to their two-bedroom flat and saw the squalor in which they were living. “They were hungry, cold. They were paying $170 a week and didn’t even have a bed. They were sleeping on dirty floors, with rats and cockroaches.”

“In a small community they are all making money from backpackers – farmers, shops, businesses – everybody is turning a blind eye. Convicted rapists can take backpackers into their houses.”

Polsoni took them to her home. Later, when she came across a group of Asian men in a paddock and discovered they were starving because they hadn’t been paid, she organised donations and delivered them boxes of food. “The exploitation of Asian backpackers is easier than Europeans. They would rather employ Korean, Taiwanese and Chinese. That was a strawberry farm … which supplies to Coles. I phoned Coles and said, ‘You have got 24 hours to get that farmer to pay them, or I will go to the media.’ ”

Rosie Ayliffe only started to discover the “mass exploitation” when she came to Australia from England to collect the body of her daughter.

Ayliffe had been relieved when her only child, Mia Ayliffe-Chung, had arrived in safe, shiny Australia. But on August 23 last year, Mia had been murdered at a hostel in Home Hill, Queensland. She had been stabbed to death by Smail Ayad, 29, from Marseille, France, with whom she was sharing a dormitory. “I realised that the way backpackers were being forced to live must have had a contributory effect,” Ayliffe says.

Mia’s friend Tom Jackson, who had tried to save her, also later died from more than 20 stab wounds.

Ayliffe has since become a campaigner for legislative changes concerning conditions for backpackers. “I am contacted at least once every day by someone who has come out of a situation or is right in the middle of a situation,” she says.

Ayliffe knows of a girl who used a washing machine without permission and was tipped into the street at 2am by a hostel owner.

Sexual harassment of young women is rife. “Farmers making them have sex before they would sign them off,” she says.

Polsoni rescued a girl from a farm in Murgon, Queensland. “There were no locks on the bathroom doors and she found a camera in the shower. She was continually approached for sex. When she said no, the next day she was put on the farm for 15 hours straight. When she wanted to leave he refused to pay her.”

Ayliffe dealt with a 21-year-old girl from the Netherlands who had become frightened when a farmer was violent towards his stock and pets, and threatened to shoot any authorities who got involved. When the police came they had on bulletproof vests. “People are sitting by and watching while young girls are going into the houses of people who are known to have instability. And yet they had done nothing to stop him taking more backpackers. In a small community they are all making money from backpackers – farmers, shops, businesses – everybody is turning a blind eye. Convicted rapists can take backpackers into their houses.”

Backpackers and migrants are often expected to work 14-hour days in the heat without being provided water, food, toilets or training. Hard, gruelling work; the dirty work Australians don’t want to do, in conditions in which they would not tolerate their own children working.

“They can be asked to use farm machinery which they have had not been inducted in,” Ayliffe says. “They are being hospitalised. An Irish woman was told to clean a moving conveyor belt – she was scalped and lost an ear. Mia was given absolutely no health and safety induction or told how to deal with snakes. It has been going on for decades and there have been bodies going home for decades. ”

This week, a distressed Salvatore Cudjoe from Verona, Italy, told The Saturday Paper he spent the past two months working for a contractor he knew only as Mustafa. “They promise you so many things. I picked zucchini, passionfruit, tomatoes, ginger, sweet potatoes. He wasn’t paying tax. He wouldn’t let us fill out the form – no company, no surname.”

Cudjoe was paid small amounts to buy food, but now Mustafa has vanished, owing Cudjoe and a number of other backpackers thousands of dollars. “Can you help me?” a destitute Cudjoe asks.

Almost every week there is another story of a rogue labour-hiring rort. The Queensland industrial relations minister, Grace Grace, calls it “a national disgrace”.

At the moment, Polsoni says, “the Fair Work Ombudsman can only go so far because they do not have the authority to enforce a payment to a client and the police say it is a civil matter. A lot of community services can’t help them because they are not citizens. There needs to be better regulation; the Fair Work Ombudsman needs more authority to act on behalf of the backpackers. There needs to be more stringent monitoring.”

She says backpackers are also often not in the country long enough to see through Fair Work’s complaints procedures against recalcitrant employers.

Rosie Ayliffe is back in Australia and was in Canberra this week to meet politicians. On Monday, she will speak in Mildura at the parliamentary inquiry into establishing a modern slavery act in Australia, as Britain has done.

She had thought Mia would be safe at Home Hill because her daughter was in a government scheme that would be regulated and only involve compliant businesses. She was tragically mistaken. Now she knows there is a long way to go towards reform. “You should have licensed operators on a federal level. Your health and safety is amazing. Your work place laws are fantastic. They just don’t extend to your migrant workers.”