Workers who blew the whistle on their treatment by a telecommunications' subcontractor say they have been harassed by a lawyer and their former employer.
The Labour Inspectorate is taking 3ML Services to the Employment Relations Authority (ERA) for underpaying migrant workers and failing to keep employment records.
3ML was subcontracted by UCG and Visionstream to roll out ultra-fast fibre broadband for Chorus in Auckland, however the firm was blacklisted after its employment breaches were revealed.
A former 3ML employee, Baljit Pal Singh, said 3ML director Roderick Laus contacted his friends and family to ask him to settle his $14,000 pay dispute privately.
"They are asking [my friends who still work at 3ML] to contact me, so I am receiving calls around 10pm, 11pm at night."
A cease and desist letter another worker sent to Mr Laus and his lawyer, Simon Graham, in December said they felt threatened.
"I have found your continued attempts to compromise me as a witness and whistle-blower in the case of migrant abuse at hand to be intimidating, coercive and inappropriate," the letter said.
"I feel threatened by receiving correspondence from you and you must cease and desist immediately."
Neither Mr Laus nor Mr Graham responded to RNZ's requests for comment.
Another former 3ML employee, Thomas Shepherd, said three workers sent cease and desist letters but another worker had signed a settlement.
"We understand that although he signed a non-disclosure agreement with that . . . he actually received no money from that.
"It was basically a, 'We'll leave you alone, you leave us alone' [agreement]."
Mr Shepherd said concerns over the harassment had been raised with the Labour Inspectorate, but it would not intervene.
"The Labour Inspectorate have made it clear that they are impartial.
"There is only so much that we can do, we are just blue-collar workers, we are not wealthy, we cannot hire a lawyer."
Labour Inspectorate regional manager David Milne said he was aware 3ML's lawyer had tried to contact the workers last year but understood they refused to engage.
He referred any concerns about the treatment of 3ML workers to the ERA.