In the absence of agreement by the parties on the procedures for appointing the arbitrator or arbitrators:
1° In the case of arbitration by a sole arbitrator, if the parties do not agree on the choice of arbitrator, the arbitrator shall be appointed by the person responsible for organising the arbitration or, failing that, by the supporting judge;
2° In the case of arbitration by three arbitrators, each party shall choose one and the two arbitrators thus chosen shall appoint the third ; if one party does not choose an arbitrator within one month of receipt of the request to do so from the other party or if the two arbitrators do not agree on the choice of the third within one month of acceptance of their appointment, the person responsible for organising the arbitration or, failing that, the supporting judge shall make the appointment.