Generally the Arbitration agreement provides for sole arbitrator only if all parties to the dispute consent for the person selected. If few agree and others do not, then the discenting parties may file an application before the court for appointment of an arbitrator by it. Or if the Arbitration agreement provides for appointment of board of Arbitrators, then the discenting parties should appoint co arbitrator/s wihtin the time stipulated in the agreement which is normally one month from the date the dispute is raised. Even if the sole arbitrator in ur case started the proceedings inspite of objection raised, u may apply to the court for stay of proceedings and appointment of court arbitrator. This should be done without delay.