The Fair Work Ombudsman pursued Kamaldeep Singh and his wife Uma Singh in court last year, winning orders for them to pay $120,000 and $90,000 respectively over their conduct while they ran the Metro Petroleum service station on the Pacific Highway at Doyalson.

The service station has since changed hands and the watchdog says it has no concerns about its present owners.

Mr and Mrs Singh were director and manager of Sinpek Pty Ltd. The company, in liquidation, underpaid two employees a combined $52,722 between May 2015 and the man and woman's termination in August 2016.

The workers were Indian nationals from non-English speaking backgrounds hired as console operators. Both workers were on bridging visas and seeking sponsored migration via Sinpek before they were fired.

Federal Circuit Court Judge Sandy Street said the workers were vulnerable due to their immigration status and the Singhs "exploited those vulnerabilities knowingly, and to their own advantage and for their own benefit".

She also accused the company of seeking to avoid its obligations by entering liquidation.

"[The employees] moved interstate under the inducements of [Mr and Mrs Singh] and... were placed in a position of threat of return to India or being deported if they failed to accommodate the exploitation by [Sinpek, Mr Singh and Mrs Singh]," Judge Street said.

"The conduct of the respondents in the circumstances of the present case is at the most serious end of the spectrum in respect of each of the contraventions."

The ombudsman said the female employee, who was shorted $28,114, was paid nothing for her first three months' work.

The court found that the Singhs failed to pay minimum wages, penalty rates, shift loadings and to honour leave entitlements under the award. They also failed to provide payment in lieu of notice when the pair were sacked, or to keep records or proper payslips.

Mr Singh was also accused of requiring the male employee to cover the cost of a driver who left without paying for fuel, and required the man to also pay part of Sinpek's income tax obligations relating to his own work.

The company went into voluntary liquidation in July 2019, three weeks before the scheduled penalty hearing. The ombudsman confirmed on Wednesday that a subsequent appeal had been dismissed.

Acting ombudsman Jeremy O'Sullivan said the size of the penalties reflected how serious the matters were.

"All employees in Australia have the same rights at work, regardless of citizenship or visa status. We encourage anyone with concerns about their wages or entitlements to contact us," Mr O'Sullivan said.

All underpayments have been rectified, with interest.