Sullivan, who had been hired as a casual employee moved to a full-time position working long hours, but no contract was signed for the position change.
The disagreement between Sullivan and Singh began on November 1, 2018, when he spoke to her about some accumulated store debt that she needed to pay off.
She could not pay the debt on the spot as she had left her wallet at a friend's house, the decision said.
When Sullivan was on her way home Singh called her, demanding "in an angry and aggressive tone" that she come back to the store and pay the debt of $255.
"Ms Sullivan claimed Mr Singh used profane language in the call, a matter Mr Singh denied," the decision said.
Sullivan said she would pay the debt in the morning when she arrived at work, but later agreed to make a bank transfer, which she did not do.
In one of Singh's text messages, he told Sullivan the "f***ing" suppliers were "on my ass" needing to be paid.
Sullivan texted Singh that evening saying she was going to take the next three days off work as she was stressed and had just worked 10 days in a row. She also said she planned to limit her future hours to "around 40 to 50" per week.
"I'm not being spoken to like that. I don't own the business and its not my fault the suppliers want money," she told him.
"I am getting stressed being at work all the time to help you ... I love my job and I work hard."
Later that evening, Singh emailed Sullivan with the subject line "first written warning" saying she often had excuses to be away from work on busy days, and it was now affecting the business.
"You are very hard working and honest person but [you] need to take responsibility not be away from work on busy days of the week."
After seeing the email and becoming angry, Sullivan stopped the bank transfer she had put in place to pay the debt.
The next morning the pair texted back and forth about the payment that hadn't come through, with Sullivan admitting she cancelled the payment.
Singh then sent her an email letting her know she was fired and would be receiving no more shifts at the shop. He said her debt would be deducted from the paychecks she was owed.
He said she had broken his trust and was "misbehaving", and was away from work when needed.
ERA member David Beck found the process Singh went through was "procedurally deficient" and regardless, the dismissal was unjustified.
"Mr Singh sadly overreacted and behaved in an unnecessarily overbearing manner," he said.
Beck ordered Singh to pay $4872 in lost wages, $78 in holiday pay, and $15,000 compensation for the unjustified dismissal.
"With some justification, Ms Sullivan felt Mr Singh had been angry and verbally abusive to her and then dispensed with her services in a callous fashion," Beck said.
"The timing of the dismissal led to uncertainty over the Christmas period and Ms Sullivan indicated worry about meeting financial commitments and that she was unable to afford suitable Christmas gifts for her then 8-year-old daughter and grandchildren."
She also described a strain on her personal relationships, ill health, difficulty sleeping, and a tendency to burst out crying. Sullivan said she had to take an increase in anti-depressant medication.
Beck also ordered Singh's business, Erman Private Ltd, to pay $3000 towards Sullivan's legal costs.
In his submissions to the ERA, Singh made a "reparation claim" for $50,000 again Sullivan, citing his stress from having the grievance laid against him.
"Even if the Authority was minded to consider this claim, its late nature and complete lack of justification prevents it proceeding," Beck said.
