5Each of the parties to the arbitration shall within fourteen days from the appointment of the arbiter deliver to him a statement of that party's case with all necessary particulars ; and
(a)no amendment or addition to the statement or particulars delivered shall be allowed after the expiration of the said fourteen days except with the consent of the arbiter;
(b)a party to the arbitration shall be confined at the hearing to the matters alleged in the statement and particulars so delivered and any amendment thereof or addition thereto duly made.