Allegations have emerged that Filipino massage workers were brought to the ACT, packed into a crowded home, underpaid, overworked, subjected to a curfew, and banned from socialising.
Now, the Salvation Army and a union which helped expose the "appalling" case are calling on both the Coalition and Labor to better prevent workers from being exploited through the 457 temporary visa process.
Roughly 14 workers are thought to have been mistreated, according to investigations by the Salvation Army and United Voice.
Witness statements from the workers allege many were approached in hotels or massage parlours in the Philippines, where they worked as massage therapists.
They signed legitimate contracts, but allegedly arrived in Australia to find the reality of the work was far from what had been promised.
Workers allege their passports were initially confiscated, and they were forced to live in a cramped home in Canberra, which housed between 10 and 18 workers at a time.
They say they worked 12-hour days, six days a week, and were forced to withdraw large chunks of their cash and return it to their employer.
The gate to their home was said to be padlocked at night, and the workers allege they were driven to and from work in a van each day, and were banned from socialising, bringing anyone to the house, or having boyfriends or friends outside work.
Potential deportation was used as a way of reminding them not to break "the house rules", the workers allege.
Fairfax Media is unable to identify the business or workers involved for legal reasons, but has sighted witness statements from those involved, as well as payslips and bank statements supporting the allegations.
Police investigated the claims but did not lay charges for any criminal offences, an ACT Policing spokeswoman said.
The Fair Work Ombudsman also investigated claims of exploitation following requests for help from the workers. That prompted the business to rectify a number of matters, the ombudsman's office said.
A spokesman for the ombudsman said investigations were continuing, and that no further comment could be made.
United Voice ACT secretary Lyndal Ryan said the case again showed how easily workers on 457 visas – temporary visas designed to remedy skill shortages – were being exploited.
She called on the Coalition to commit to implementing better protections for workers ahead of Saturday's federal election. She said Labor had already made such commitments during the campaign.
"The system is suiting the exploiters at the moment, and I guess until it happens to your kids you might not care," Ms Ryan said.
The union fears that 457 visas allow employers a dangerous level of control over vulnerable workers.
Employers were given power because a termination of employment, particularly easy during probation periods, would force the worker to leave the country in most cases.
Ms Ryan said more oversight and monitoring of the scheme was needed, including a liaison officer to ensure workers are not mistreated and know their rights.
"Was there really a skills shortage in the massage parlour?" she said.
"Or are we just creating a system that allows a large number of people to be exploited?
"When you deprive of people of their liberty and let them have no control it is akin to slavery."
Some of the workers have since been afforded bridging visas. Others have returned home.
The Salvation Army has been campaigning for a tougher approach on slavery and human trafficking, advocating for more prosecutions to take advantage of recently-amended anti-slavery legislation.
National policy and advocacy officer Heather Moore said the case demonstrated how employer sponsorship can be used to keep vulnerable foreign workers in exploitative work.
"Anti-slavery legislation was strengthened in 2013 to help deal with this problem, but there haven't been any prosecutions to clarify what constitutes coercion and abuse of power and vulnerability," she said.
"Increasing protections for foreign workers is step one, but we also need to resource the anti-slavery framework and make sure its implementers have the tools to carry it out."
The issue of 457 visa exploitation was examined by the Senate's education and employment references committee, which released a report in March.
It found those on 457 visas were vulnerable to exploitation, although cases had reduced due to greater monitoring.
JobWatch, an employment rights legal centre, said it regularly received calls from temporary visa workers.
In 2014 it had 43 callers who identified themselves as 457 visa holders.
It told the committee of eight case studies which showed underpayment, unfair dismissal, a lack of entitlements, discrimination, contravention of visa conditions, harassment, deportation threats, or employers requiring payment for sponsorship.
Trade unions also presented evidence of cases of 457 visa exploitation to the committee.