(1) A person who complies with a requisition under section 30(1)(b), 30(2), 33(1)(b) or 33 (2) shall -
(a) be given an opportunity of having an additional specimen of blood taken by a registered medical practitioner of his own choice or of giving an additional specimen of urine to that practitioner, or
(b) if the person so requests, be supplied by the designated registered medical practitioner with an additional specimen of blood taken from that person in accordance with the prescribed procedure immediately after the taking of the specimen in pursuance of the requisition or, where a specimen of urine has been provided, with portion of that specimen.
(2) In a prosecution for an offence under section 49 or 50 of the Principal Act or under section 30(3) or 33(3) of this Act, it shall be presumed until the defendant shows otherwise that the requirements of subsection (1) have been complied with.
(3) Where the defendant gives evidence to establish that the provisions of subsection (1)