It shall be unlawful and an unfair trade practice for any person to cause to be placed before the public in this state, directly or indirectly, any false, misleading or deceptive advertising matter pertaining to primary or subordinate mortgage loans or the availability thereof: Provided, That this section shall not apply to the owner, publisher, operator or employees of any publication or radio or television station which disseminates such advertising matter without actual knowledge of the false or misleading character thereof.