An Auckland tradie who lost his job following a complaint over his alleged flirting with a customer has been awarded more than $22,000 in compensation.

The Employment Relations Authority found assistant roofing technician Samuel Newman, who was also a health and safety supervisor, to have been unjustly dismissed by his employer and suffered unjust disadvantages.

The Authority ordered Solid Roofing to pay Newman $22,875 in compensation for humiliation, loss of dignity and injury to feelings and lost wages.

Newman, 22, was dismissed in January after a written warning following a customer complaint in respect of damage to a property and "unprofessional behaviour".

Following the written warning Newman had a heated discussion with Solid Roofing director Peter Vandenberg. Newman told the Authority the phone call ended with Vandenberg hanging up and telling him he was stood down until further notice.

Newman claimed his dismissal was unjustified, which Vandenberg denied. He said there had been numerous complaints about Newman and his work performance.

Vandenberg said Newman was warned about his performance prior to the written warning, which came following a serious customer complaint.

He said Newman was given a verbal warning for failing to provide a safety analysis on a job.

Newman was called into a meeting with Vandenberg in January who discussed a job he had been working on in the Auckland suburb of Cockle Bay with supervisor Jamie Cameron. Vandenberg told Newman the customer was not happy with the end result and asked about the customer's actions towards him.

The Authority heard there was a lot of joking at Solid Roofing's Christmas party about Newman's interactions with this customer.

Newman said the customer had been flirtatious with him, offered him ham and cheese croissants, a drink and asked him to come inside her house.

Other than accepting a glass of water, Newman said he refused her requests.

Vandenberg said he received a call from the customer's husband about the quality of the work and was told about alleged sexual innuendo and banter between Newman and the female customer.

Newman denied this and said this was not discussed at the meeting.

The Authority found Vandenberg had not fully investigated the alleged "serious" complaint and accepted Newman's version of events, and that the customer had acted flirtatiously towards him rather than the other way around.

"Rather, the customer's husband was annoyed by the attention his wife was paying to Newman and Cameron working with their shirts off," outlined in the decision.

In its decision the Authority said the written warning issued on January 15 was not only "substantively unjustified, but procedurally unfair", written before the meeting between Newman and Vandenberg took place.

"In my view, the reasons and manner of the written warning were not the actions of a fair and reasonable employer," Authority member Anna Fitzgibbon said.

Fitzgibbon said Vandenberg's actions had a significant impact on Newman, who had "suffered physically, mentally and went from being a confident person to being apprehensive".

Newman said he felt betrayed by Vandenberg and humiliated by the way he was treated. He said he lost his appetite, had difficulty sleeping and was stressed.

"Mr Vandenberg acted in careless disregard of his obligations as an employer to Mr Newman. Mr Vandenberg failed to treat Mr Newman in good faith and failed to provide him with wages and time records when requested," Fitzgibbon said.

He also failed to respect the Authority's investigation process, she said.

"Solid Roofing had ample opportunity to comply with its statutory obligation, it deliberately chose not to."

Vandenberg told the Herald he would lodge an appeal against the decision.

"We've got very good grounds to lodge an appeal," he said.

"I was absolutely gobsmacked, gobsmacked that this can happen in this country.

He said the Employment Relations Authority was biased:

"The unfortunate thing is every employer out there is in the same boat. It is so biased in favour of the employee...I gave someone a job with the best intentions."