One of South Australia's biggest employers, the On The Run convenience store chain, is under investigation by the State Government following reports its traineeship program is a sham designed to keep wages low.

Key points: Chris Norman says he was required to do an automotive traineeship to work at Hungry Jacks inside On The Run

Chris Norman says he was required to do an automotive traineeship to work at Hungry Jacks inside On The Run Trainee wages were $15.30 an hour, compared to average adult wage of $19

Trainee wages were $15.30 an hour, compared to average adult wage of $19 Former manager say staff were also made to sign waiver for overtime wage loading

Former manager say staff were also made to sign waiver for overtime wage loading On The Run maintains it has 'best traineeship program in Australia'

With more than 125 stores across the state and more than 2,000 employees, On The Run's 24-hour fast food, petrol and convenience store chain is one of South Australia's fastest growing businesses.

Every employee signs the company's promise: "We Never Close."

But in the wake of the wage underpayment scandal engulfing the country's 7-Eleven franchise operations, the company's business model has come under increasing scrutiny.

Former trainees and managers have spoken to the ABC's 7.30 program, many too afraid to speak out publicly.

Law student Chris Norman, 23, is one employee who decided to stand up.

He was required by On The Run to do a Certificate II in Automotive Sales, even though his job was at a Hungry Jacks based inside an On The Run petrol station.

Mr Norman said his job was so different to the training content that On The Run's human resources staff had to provide the answers.

As a trainee, he was paid just $15.30 an hour.

"I didn't want to let them step on me, I wanted to stand up, 'cause it wasn't just happening to me, it was happening to everyone," Mr Norman said.

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Business using obscure sub-clause to pay trainee wages

Mr Norman sought the services of a lawyer, who wrote to On The Run requesting he be backpaid more than $800 in lost wages.

That lawyer, Joseph Wearing, said Mr Norman should have been paid closer to $19 an hour.

Through his correspondence with On The Run, Mr Wearing discovered the business used an obscure sub-clause in the Vehicle Manufacturing, Repair, Services and Retail Award 2010 to justify paying their trainees even less than the normal trainee wage because they were provided with "on the job" training.

"I mean the traineeship rate was already lower than the hourly adult rate," Mr Wearing said.

"But the on-job training rate was 20 per cent lower again."

Mr Norman said he received barely any training at all, and none of it was relevant to his job at Hungry Jacks.

"We had a one-hour staff meeting once a month, where the HR manager came out and we got worksheets, these worksheets were related to automotive sales, so they didn't really have anything to do with Hungry Jacks," he said.

Mr Norman said he and his colleagues could not answer the questions, so were given the answers by a HR manager.

Mr Wearing said the conclusion to draw was that the training was used to reduce Mr Norman's pay rate.

"Because the training had nothing to do with the job that he was doing, it was only serving to justify the reduction in his rate of pay," he said.

Former manager says staff had to waive rights to overtime wages

Mr Norman eventually reached a confidential settlement with On The Run and is currently unemployed.

But it is not just the trainees who are impacted by the company's aggressive wage minimisation techniques.

One staff member, who asked not to be identified for fear of reprisal, worked as a manager for four years.

He said managers were required to sign away their rights to an overtime wage loading in a form attached to their contracts.

"The form was just handed to us as part of our contract, where you sign here, here, here and here," he said.

"And if you don't sign the last page, they're not going to offer you that contract."

Company maintains it has 'best traineeship program in Australia'

Complaints by former On The Run staff were so widespread that a Boycott On The Run Facebook page attracted almost 2,000 likes before it was removed four weeks ago.

The posts on that page were similar to the stories told to 7.30 by many current and former trainees and managers.

On The Run has declined to comment.

However, the company has previously said it runs the "best traineeship program in Australia", and that everything they do is "fair and legal".

Mr Wearing said On The Run's traineeship program calls into question the government body charged with policing these traineeship arrangements.

"There needs to be a proper oversight of these training arrangements to ensure that training is being provided, that the training is relevant to the job that's being performed in all cases," he said.

SA Skills Minister Gail Gago has confirmed her department is investigating On The Run's traineeship program, but the Minister herself declined to be interviewed.