NASHVILLE, Tenn. — The National Labor Relations Board has filed another unfair labor practices complaint against Volkswagen for hiking health insurance premiums and changing working hours of employees who voted for union representation at the German automaker’s only U.S. plant.

Volkswagen is in the midst of a legal challenge to NLRB rulings in favor of the small group of skilled-trades workers at the plant in Tennessee who voted for United Auto Workers representation.

But the NLRB said the federal appeals court case in Washington doesn’t override the UAW’s exclusive collective-bargaining rights for the workers who maintain and repair the plant’s machinery and robots.

Volkswagen spokesman Scott Wilson said in an email that the company wants the entire blue-collar workforce at the plant to decide labor issues, not just the skilled-trades workers.