(a) Except as provided in subpart (b) of this section, no insurer may hereafter use a class plan, or charge or collect a premium which does not comply with the provisions of this subchapter or with the provisions of the California Insurance Code. No insurer may offer, sell or renew a policy of automobile insurance, or collect a premium for a policy of automobile insurance which is not calculated in accordance with a class plan that complies with this subchapter.

(b) Prior to the approval of a class plan which has been submitted to the Commissioner in good faith and which complies with the provisions of this chapter and the Insurance Code, an insurer may continue to use rates and premiums that are calculated pursuant to a class plan that has been approved by the Commissioner.