A supermarket worker who described her boss as a "bitch" in a conversation with a colleague was unjustifiably dismissed and has won almost $13,000 in lost wages and compensation.

Raeena Naiker was an assistant in the seafood department at Pak'nSave Porirua for two-and-a-half years until she was dismissed in March last year.

Naiker, according to a recent Employment Relations Authority decision, had a difficult relationship with her manager and claims to have been bullied.

She developed a health issue last year and required two weeks off work. She didn't have enough sick leave and contacted her manager to see if she could take annual leave.

The company refused and after a meeting over the issue, Naiker said she became upset because she believed the supermarket was being unfair.

Once the meeting was over, she went to the staff tearoom where she had a conversation with a friend, Sialuga Talo, who worked as a supervisor in another part of the supermarket.

Naiker said she complained to Talo about her manager's behaviour and described it as bullying.

Talo told the ERA that she heard her friend out without advising her that she felt uncomfortable with her comments and how she was expressing herself.

Talo reported the conversation to the supermarket's fresh food manager, Daniel McKissock, who asked her for a statement and requested that another worker in the tearoom do the same.

Talo said Naiker had called her manager a "bitch" because she was angry that others were allowed to take leave but she wasn't.

"F***, man, other staff are allowed to take leave but not me. Bitch," Talo's statement said.

The other worker who was also in the tearoom, Jarrod Gardiner, said Naiker had swore and used the language "f***ing bitch".

Naiker was asked to attend a formal meeting to respond to allegations of serious misconduct for using abusive language and engaging in malicious or damaging gossip.

Naiker was dismissed after a series of meetings attended by a union legal officer and Pak'nSave Porirua's Martin Fryer.

Fryer told the ERA that his decision to dismiss Naiker was based on him accepting Gardiner's evidence that Naiker had referred to her manager as a "f***ing bitch".

He said the word "bitch" on its own did not hold the same weight and it was the combination that made the behaviour serious misconduct. He did not accept that the conversation between Naiker and Talo was private.

Talo, in her evidence to the ERA, said she also remembered Naiker "using the f-word too".

She could not explain why that was not recorded in her written witness statement.

ERA member Trish MacKinnon was not persuaded Naiker used the words "f***ing bitch" and that Talo's written statement was more likely to be accurate.

"As such, by Mr Fryer's reasoning, there was no reason for the company to dismiss Ms Naiker," MacKinnon said.

"While the language was robust and forcefully expressed, it is not uncommon
language in the workplace. Mr Gardiner, under questioning, acknowledged that
swearing was normal and commonplace in his work group.

"It was not directed towards Ms Talo, in whom Ms Naiker was confiding her frustration, but was an expression of anger and frustration over what seemed to Ms Naiker to have been unfair treatment," MacKinnon said.

"Even if Ms Naiker had used the two words in combination, which I find she
did not, it was in the context of a private conversation she was having with a fellow employee she believed, mistakenly as it eventuated, to have been a friend," the ERA member said.

"The conversation was not intended for broadcasting to a wider audience and was not intended to be heard or conveyed to the persons she was speaking about. In those circumstances I find it was not the action of a fair and reasonable employer to dismiss Ms Naiker," MacKinnon said.

MacKinnon said that letters of instruction to Naiker in 2015 were also used as part of the justification for her dismissal and that appeared unfair.

None of those three letters concerned the use of abusive language.

"I find the employer's investigation to have been defective and its decision to dismiss Ms Naiker to have been an action that a fair and reasonable employer could not have taken in all the circumstances at the time," MacKinnon said.

The ERA ruled that Naiker's dismissal was unjustified and accepted that she was humiliated by it.

MacKinnon ordered Pak'nSave Porirua to pay her three months' wages of $6739 and $6000 in compensation.