The Alphabet Workers Union, which aims to represent workers at Google, announced it filed an unfair labor practice charge against Modis, a division of Adecco. The union said in a tweet that Modis told workers not to talk about wages and allegedly retaliated against a union member.

“Alphabet is a trillion-dollar company yet it uses [temporary workers, vendors and contractors] to save money & ensure flexibility, giving workers fewer benefits & laying them off at will,” the union wrote in another tweet. “This practice must end. We can’t pretend to be an ethical company if half our workforce are treated like second-class citizens.”

As reported by Business Insider, the union said Shannon Wait, a worker in South Carolina, was suspended after she complained about the ban on discussing salaries and a refusal to replace damaged water bottles. Wait had also previously asked why some workers had not received promised bonuses.

Alphabet is the parent company of Google. The union was announced in January and aimed to include all types of workers from directly hired to contingent.