54. When any person is possessed of a stamp or stamps which have not been spoiled or rendered unfit or useless for the purpose intended, but for which he has no immediate use, the Collector shall repay to such person the value of such stamp or stamps in money the words deducting six and one-fourth per centum of that value upon such person delivering up the same to be cancelled, and proving to the Collector's satisfaction-(a) that such stamp or stamps were purchased by such person with a bona fide intention to use them; and (b) that he has paid the full price thereof; and (c) that they were so purchased within the period of six months next preceding the date on which they were so delivered: Provided that, where the person is a licensed vendor of stamps, the Collector may, if he thinks fit, make the repayment of the sum actually paid by the vendor without any such deduction as aforesaid.