Every estate agent who is the sole proprietor of an estate agency business or a partner in a partnership or a director of a company or a member of a close corporation contemplated in paragraph (b) of the definition of "estate agent" in section 1 of the Act carrying on the business of an estate agent, shall be held responsible for any contravention of or failure to comply with this code of conduct by any other partner, director, or member or by any estate agent in the service of such sole proprietorship, partnership, company or close corporation, unless he has prior to such contravention or failure to comply taken all reasonable steps to prevent the same and could not in the circumstances have prevented such contravention or failure to comply.