If any dealer collects any. amount by way of additional tax or purporting to be by way of additional tax, in contravention of the provisions of sub-section (2) of Section 2, the assessing authority concerned may, after, giving such dealer a reasonable opportunity of being heard, by order in writing impose upon him by way of penalty, a sum not exceeding one and a half times of such amount:
Provided that no proceedings under this section shall be commenced after a period of five years from the expiry of the year in which the amount has been collected.
Provided further that no prosecution for an offence under sub-section (3) of Section 2 shall be instituted in respect of the same facts on which penalty has been imposed under this Section.