Google subcontractor Modis Engineering, a subsidiary of the staffing firm Adecco, is facing a labor complaint alleging it illegally retaliated against an employee who raised concerns about pay and working conditions.

Alphabet Workers Union, which is part of the Communications Workers of America and advocates on behalf of Google workers, filed a complaint with the National Labor Relations Board on Thursday on behalf of Shannon Wait, a Modis employee in South Carolina.

AWU said in a press release that Modis, which maintains data centers on behalf of Google, illegally suspended Wait after she complained about the company's ban on discussing salaries. Wait had previously asked managers why some employees hadn't received bonuses as promised, according to the AWU.