The star of Ten's Good Chef Bad Chef is the latest high-profile restaurateur to run foul of Fair Work laws, after George Calombaris recently repaid $2.6 million to more than 160 staff, while Ronnie Di Stasio was forced to pay $35,000 to six foreign workers found to have been exploited at Cafe Di Stasio in St Kilda.

ACTU president Ged Kearney said underpayment was so pervasive in the hospitality and retail sectors that it had become a business model for many employers.

Fairfax Media has been told one La Luna employee was repaid up to $10,000, after she was routinely denied basic entitlements. But the reimbursement was conditional on the woman signing a non-disclosure contract in an apparent bid to avoid negative publicity.

Another young kitchen hand, who started at the Rathdowne Street eatery as an 18-year-old, was paid a flat-rate of $14 an hour for more than six months.

"I went to Fair Work and found out I should be getting about $21. They [management at La Luna] claimed it was mistake and agreed to give me back pay."

The young man was recently reimbursed $3165 for underpayments over a 12-month period, but has since left the restaurant.

A former waitress said she never received penalty rates for weekend work at La Luna. The woman claimed Mr Richardson had advised some staff that a "workplace agreement" was in place that exempted him from paying penalty rates.

The woman says she is owed more than $7900, while Mr Richardson had offered to reimburse $3589.

"They never paid me what I was entitled to the whole time. I called Fair Work and they confirmed it," she said.

A spokesman from the Fair Work Ombudsman said it had received several enquiries from staff employed by La Luna Bistro Pty Ltd.

"The Fair Work Ombudsman has been assisting these workers. We cannot make further comment at this stage".

Three other La Luna staff said they were owed thousands of dollars by Mr Richardson, with one set to ask the ombudsman to formally investigate the restaurant.

"When I came to La Luna, I assumed we were getting paid properly. I have no idea what this agreement was that he [Adrian Richardson] was talking about. We are all really upset and many of them have just decided to leave," a former waiter told Fairfax Media.

"I'm not happy about what's going on, that's why I left. I want to wash my hands of the place."

Mr Richardson, who also stars on Foxtel program Secret Meat Business, did not respond to repeated requests for comment.

In 2015, Mr Richardson claimed he had received death threats from "tofu-munching food extremists" after he'd declared on television he would cook anything with a pulse.

"There are a bunch of food terrorists out there. I get death threats. They tell me I'm a murderer. I get nasty letters and on Twitter there is a stream of some of the most offensive language against me," Mr Richardson told News Limited.

His restaurant, La Luna Bistro, has been a mainstay on Melbourne's fickle culinary scene.