SAG-AFTRA has filed unfair labor charges against Grey Global, accusing the giant ad agency of using a “front company” to skirt the union’s contract to produce nonunion TV commercials. The charges, filed today with the National Labor Relations Board, claim that Grey Global used a company called 23 Townhouse to produce the ads with nonunion actors.

The union began investigating the alleged ruse to bypass its contract last month. At that time, Grey Global said that there was “no merit” to the union’s allegations and reiterated that today when contacted by Deadline. “There is no merit to their contentions, and we are taking appropriate legal steps to respond,” spokesman Owen Dougherty said.

The union, which says its investigation is ongoing, is asking its members to be on the lookout for ties between the companies when working on commercials for the ad agency.