SKT director Matt Docherty alerted Mortimer to the complaint and said she would be suspended on pay while the matter was investigated.
Docherty emailed a letter headed "immediate suspension", saying the company would be investigating a "serious complaint laid in writing by one of your clients".
The company alleged Mortimer had attempted to discipline a client's child, that she had called a colleague a "bitch", had openly discussed the company's confidential restructuring plans, swore in front of a client and her children, failed to complete nail treatments to an acceptable standard, and that she had told a client a colleague's work was "terrible and that she wasn't good at her job".
At a disciplinary meeting soon after, Mortimer apologised for having called a colleague a bitch to a client, and had made the comment because she was unsettled after what she considered was an unexpected restructuring meeting earlier that day.
The client who alleged Mortimer had disciplined a child also said she had "criticised the lack of control of children at a children's princess party held at the salon".
Mortimer raised personal grievances two days after she received the letter from her employer on April 29 and again on May 9, in relation to the suspension and a redundancy proposal process that had begun.
She argued the suspension was unjustified and told the ERA there was no consultation, and that SKT could have considered other options while it investigated.
Mortimer claimed the dismissal was unjustified because SKT did not tell her the investigation might result in dismissal; it had not previously warned her about the issues she was dismissed for; did not give her an opportunity to be heard; predetermined the outcome and did not sufficiently investigate the client complaint before making a decision.
SKT said its actions were justified because it believed Mortimer's behaviour was erratic and there was a risk to its reputation if she was to continue in the workplace during its investigation.
The company said it was justified in dismissing Mortimer for serious misconduct because it considered its commercial reputation was at risk if it continued to employ her.
ERA member Antoinette Baker said in her decision this month that Docherty could only refer to two discussions he had with Mortimer about the behaviour that SKT called a similar "pattern" in its dismissal letter.
One of them had sprung from a comment Mortimer had made to a client, who she didn't know was Docherty's sister.
The ERA was not satisfied that SKT had found a pattern of behaviour to support a finding so serious that it could not trust Mortimer to continue in her employment.
The authority found Docherty's approach on the April 28 phone call - the morning after the client complaint, could not reasonably be regarded as consultation before deciding to suspend Mortimer.
It also said SKT's quick arrival at the view Mortimer posed a "serious risk" warranting immediate suspension was at best a serious overreaction, and not what a reasonable employer could have done in the circumstances.
It also found there was a predetermination of the decision to dismiss Mortimer for serious misconduct, although Mortimer was not successful in proving a part of her challenge over whether SKT was justified in dismissing her.
In awarding compensation, Baker found that the combination of the suspension and dismissal had a "significant emotional effect" on Mortimer.
It was the first time she had worked doing nail treatments for an employer, having previously worked from home, and the experience was likely to have affected her confidence and ability to find further work.
Mortimer, who was now back working from home as a nail technician, told Open Justice she was glad to have the tough ordeal behind her.
"It's taken a long time, and I'm now happy to have it in the rearview, and to have the determination out."
Mortimer advised anyone considering legal action over a job, to make sure the case was strong before proceeding, and to get good legal representation.
Open Justice approached Matt Docherty for comment but did not get a response.
