The request for arbitration must be sent within seven (7) working days of the decision of the Appeals Board to the representative of the Federation and the trade union representative of the Appeals Board and to the employer involved in the complaint. Upon receipt of the request for arbitration, the parties shall endeavour to agree on a neutral arbitrator acceptable to both parties. If, within seven (7) days of receipt of the request for arbitration, it is not possible to reach a mutual agreement, either party may request that the Federal Mediation and Conciliation Body submit to the parties a body composed of five (5) arbitrators. . . .