A migrant worker feared for her safety as she plotted to escape the Auckland home where she worked as a domestic servant.
First Union said Agnes Malijan, who has since returned to her home in the Philippines, was allegedly underpaid and worked 65-hour weeks.
The union planned to lodge a case for unpaid wages and holiday pay with the Employment Relations Authority on Monday.
Union general secretary Robert Reid said the worker approached them for help to escape the home.
Several union members removed her safely from the house and police were notified of the situation, he said.
"She was very nervous, understandably, and asked us not to publicise this issue till she was safe."
Reid said this case highlighted the way migrant workers were being treated in New Zealand.
"We're getting more and more stories of the exploitation of migrant workers in this country."
However, the couple who allegedly employed Malijan told One News she was a student, not an employee.
The pair said they lent her money to attend a language school and she helped around the house with chores, One News reported.
- Auckland Now
Are you happy with the council rates revaluation on your home?