(1) Where on the date fixed for hearing of the appeal or on any other date to which such hearing may be adjourned, the appellant does not appear when the appeal is called for hearing, the Tribunal may, in its discretion either dismiss the appeal for default or hear and decide it on merit.
(2) Where an appeal has been dismissed for default and the appellant files an appeal within thirty days from the date of dismissal and satisfies the Tribunal that there was sufficient cause for his non-appearance when the appeal was called for hearing, the Tribunal shall make an order setting aside the order dismissing the appeal and restore the same:
Provided, however, where the case was disposed of on the merits, the decision shall not be reopened except by way of review.