Ephraim Kalsakau, the leader of the National Workers Union, said there is dissatisfaction among seasonal workers with the level of deductions from their wages.
But Mr Kalsakau, who is also an MP, said ni-Vanuatu were afraid of losing their place in New Zealand's Recognised Seasonal Employer scheme if they complained.
However he said many workers were facing greater deductions than what they expected at the outset, for things such as transport and fuel.
"And they wonder why, I mean, they pay for transport. Surely that would include petrol, but on their payslip they pay for transport and then pay for petrol.
"So there are some grievances that our workers in New Zealand who are doing that kind of job are facing, but they don't seem to be able to have a way to deal with these disputes."
The New Zealand government last week introduced its Employment Relations Amendment Bill which is set to provide better access to unions for RSE workers.
The Bill requires that employers pass on information about unions in the workplace to respective employees along with the form for the employee to indicate whether they want to be a member.
New Zealand unionists say some Pacific workers in the RSE scheme have been pressured not to join a union.
But the bill would usher in greater protection against discrimination for union members, including an extension of the 12-month threshold to 18 months.
Meanwhile, Mr Kalsakau said fear of repercussions from the Vanuatu government and local recruiting agents was what was chiefly holding back ni-Vanuatu RSE workers from coming forward with complaints about deductions or labour issues.
"It's two forms: one is fear of the reports from the employers in New Zealand," he said.
"But I think it is more so agents and the policies of the government of Vanuatu that they are more afraid of."
The National Workers Union would be looking to partner up with a New Zealand counterpart to help ni-Vanuatu RSE workers.
"We've been working with the National Union of Workers in Australia, and we're making some headway in Australia," he explained.
"But there was no union organising the ni-Vans in New Zealand, so we didn't know who to talk to in New Zealand. It's not so important for New Zealand, but it's quite important for Vanuatu."