3 (b) that he may, if he wishes, appeal to the Appeal Board in terms of section nineteen. 17E Form and duration of licences (1) A licence shall be in the prescribed form and shall be subject to such terms and conditions as may be prescribed, in addition to any conditions fixed by the Board in terms of paragraph (b) of subsection (1) of section seventeen D. (2) A licence shall be valid for such period as may be prescribed and may be renewed on payment of the prescribed fee. 17F Cancellation of licence or imposition or variation of conditions therein (1) If at any time the Board considers that, because the holder of a licence has contravened any provision of this Act or has failed to comply with any condition of his licence or for any other sufficient cause, it would be in the public interest for— (a) the licence to be cancelled; or (b) conditions or further conditions to be specified in the licence; or (c) existing conditions specified in the licence to be varied; the Board shall give written notice thereof to the holder of the licence and shall⎯ (i) specify the grounds on which the Board’s opinion is based; and (ii) indicate that the holder of the licence may, within such reasonable period as the Board shall specify, make written representations to the Board in relation to the matter. (2) If, after considering any representations made to it in terms of paragraph (ii) of subsection (1), the Board remains of the opinion that it should in the public interest take any action referred to in paragraph (a), (b) or (c) of that subsection, the Board shall— (a) inform the holder of the licence concerned— (i) of its decision and the reasons therefor; and (ii) that he may, if he wishes, appeal to the Appeal Board in terms of section nineteen; and (b) require the holder of the licence concerned to return the licence to the Board for cancellation or for the appropriate condition to be specified in the licence or to be varied, as the case may be. (3) A holder of a licence who has been required to return the licence to the Board in terms of paragraph (b) of subsection (2) shall do so within thirty days of being notified of the requirement. (4) Any person who contravenes subsection (1) shall be guilty of an offence and liable to a fine not exceeding level four or to imprisonment for a period not exceeding three months or to both such fine and such imprisonment