Statement of case
13. The parties to the arbitration shall, within 35 days of the appointment of the arbitrator, or within such further period as the arbitrator may determine, deliver to him a statement of their respective cases with all necessary particulars and—
(a)no amendment or addition to the statement or particulars delivered shall be allowed after the expiry of the said 35 days except with the consent of the arbitrator; and
(b)a party to the arbitration shall be confined at the hearing to the matters alleged in the statement and particulars delivered by him and any amendment or addition duly made.