Where, in relation to an appeal -
(a) a hearing has commenced but is not completed, or
(b) a hearing has been completed but a determination has not been made,
by the one or more Appeal Commissioners who presided over the hearing (and the omission to complete or do the foregoing thing is due to one or more Appeal Commissioners having vacated, in whatever circumstances, office), the appeal shall, as one or more other Appeal Commissioners decide, either -
(i) be reheard by one or more other Appeal Commissioners as if the first hearing had not commenced or been completed, as the case may be, or
(ii) instead of being reheard, be adjudicated on by one or more other Appeal Commissioners in accordance with section 949U.