Reference back to arbitrator
21If in respect of an award rendered under this Act it appears to the employer or any bargaining agent affected that the arbitrator has failed to deal with any matter in dispute referred to the arbitrator, the employer or the bargaining agent affected may, within 7 days after the day on which the award is rendered, refer the matter back to the arbitrator who shall deal with the matter in the same manner as if the matter had been referred to the arbitrator under section 17.