As horrible bosses go, Simon Mackenzie has been labelled one of Perth’s worst by a court that found he had failed to pay one of his staff anything for four months — then sacked him by text after he took a sick day.

In an extraordinary ruling by Federal Circuit Court Judge Antoni Lucev, the former owner of The Curry Tree restaurant in Nedlands was ordered to pay more than $200,000 in penalties for what was described as his “egregious conduct”.

Fair Work Ombudsman Natalie James went further, saying Mr Mackenzie was guilty of “shameful exploitation of a vulnerable worker”.

Gurprit Singh, then 24, started the job on the same day he answered a Gumtree advertisement seeking an experienced cook in May 2012.

He was paid $200 in cash for his first three nights. He worked seven hours a day, six days a week for the next four months — without being paid a cent.

In September, after feeling unwell and going to a Bentley pharmacy to get a sick note, Mr Singh texted his boss saying he was not coming into work.

“For that good luck. Don’t come back,” Mr Mackenzie replied, followed by another message.

“If you don’t answer I will ring the police and say you possession of my keys to my business and I want them bak (sic),” he texted. “They will come to your house and arrest you for theft. I want my keys bak (sic) now. I have already contacted security company and changed codes. Answer your phone.”

They were not the only texts Mr Singh received from his boss.

At 5.10 one August morning, he got a text that read: “I’m gona kill u. My security company waking me f...... up. The alarm was not set last night. U c... I’m gona smash your head in. If my restaurant got broken into I would not know. U just lost more money.”

After the Fair Work Ombudsman took legal action, Judge Lucev ruled that Mr Mackenzie, whose restaurant burned down in April 2014, had breached the 2009 Fair Work Act and the 2010 Restaurant Industry Award.

The judge also personally censured Mr Mackenzie for his courtroom conduct, including a refusal to apologise and a suggestion that Mr Singh was to blame for the fire.

“Mr Mackenzie’s attitude is cause for serious concern in relation to any possible future employment by him or by any company with which he is associated,” Judge Lucev said.

Mr Mackenzie was ordered to pay more than $200,000 in penalties and $32,661 in back pay and compensation to Mr Singh.

“There is no place in Australia for this kind of highly exploitative and callous treatment of a young, overseas worker,” Ms James said.