This part shall not apply to any of the following:
(a) A duly authorized attorney at law acting in the usual course of his profession.
(b) Any admitted insurer.
(c) Any association of motor carriers.
(d) Any person who is directly or indirectly engaged, either as principal or agent, in selling or offering for sale, furnishing, or procuring any of the services described in Section 12148, 12152, or 12153, or miscellaneous service that augments or is incidental to any of those services, but who is not directly or indirectly engaged, either as principal or agent, in selling or offering for sale, furnishing, or procuring any other service described in this chapter.