It has been a year since the Federal Government promised to crack down on the exploitation of migrant farm workers, but one labour hire company still owes more than 100 of its employees hundreds of thousands of dollars.

Even though a Senate inquiry has recommended major changes to the way temporary visa holders are treated, the National Union of Workers (NUW) said employees exploited by CNC Labour Hire, were unlikely to ever get their money.

The NUW is representing 12 members owed $24,000 by CNC, but said the total amount owed was far greater.

"We estimate that there are another 100 workers that would be owed at least $200,000 for the 2014-2015 period," NUW organiser George Robertson said.

CNC Labour Hire had the contract to supply workers to the D'Vine Ripe tomato farm, in South Australia, but was exposed by Four Corners last May, for underpaying workers by up to $5 per hour.

Claire Lin came to Australia from Taiwan on a 417 working holiday visa and was employed by CNC to work at the farm.

She left the company following the Four Corners investigation and described the entire experience as a "nightmare".

After the story aired, the Federal Government set up a taskforce to target worker exploitation and visa fraud, and the ABC has confirmed the FairWork Ombudsman is reviewing a complaint about CNC Labour Hire.

The Federal Court will hear an application to wind up the company this week.

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But Mr Robertson doubts it will help members like Ms Lin, who is currently owed about $2,500.

"A decision will be handed down in court on whether to wind the company up and appoint a liquidator," he said.

"Once that happens we're dubious about whether workers will actually recover any of those lost wages through the liquidation process and so that's why we're asking D'Vine Ripe, to step in and take responsibility and ensure that those workers receive their lost wages."

D'Vine Ripe is not legally responsible to pay the workers but the union is continuing its push. It has not received a response.

The ABC has asked D'Vine Ripe for an interview but a spokesman declined, and CNC's director cannot be contacted.

Mr Roberston has concerns about the industry and said some labour hire companies move assets around in order to continue operating.

"The director of a labour hire company will shut the company down as soon as issues related to the underpayments and mistreatment of workers are raised, and will then open a new company and continue to operate in order to avoid their responsibility for those workers," he said.

A Senate Inquiry has called on the Government to set up a public register of all labour hire contractors, to try to keep track of their movements.

It has also recommended that companies should have to obtain a special license, proving compliance with tax, superannuation and employment laws, in order to operate.

A spokesman for Federal Employment Minister said the Government would carefully consider the senate report findings as part of policy it is developing in relation to vulnerable workers.