(1)An appeal shall lie to the Board of Revenue against any order by the Manager—
        (a) refusingto receive a document under section 9; or
        (b) refusing to admit a claim under the proviso to section 10; or
        (c) determining the amount of a debt or liability or of interest thereon, or reducing the rate of interest, under. section 11; or
        (d) setting asideor modifying a lease, settlement, grant, mortgage, charge or lien under section 12.
    (2)If no such appeal is preferred within six weeks from the date of the order, the decision of the Manager shall, subject to the provisions of section 22, be final.