Every rating organization shall make reasonable provision in its bylaws, rules, constitution, or otherwise to permit any insurer engaged in the kind of insurance for which rate-making is done by such rating organization to become a member or subscriber thereof upon application therefor by such insurer. An insurer may be a member of, or a subscriber to, more than one rating organization, but not for the purpose of rating the same risk. No insurer shall use any rate or rating systems made by a rating organization of which it is not a member or subscriber or by another insurer. No rating organization shall discriminate unfairly between insurers in the conditions imposed for admission as subscribers or in the services rendered to either members or subscribers. The refusal of any rating organization to admit an insurer as a subscriber shall, at the request of such insurer, be reviewed by the commissioner at a hearing held upon at least 10 days' notice to such rating organization and such insurer. If the commissioner shall find that the insurer has been refused admittance to such rating organization as a subscriber without justification, he shall make an order directing such rating organization to admit such insurer as a subscriber. If he shall find that the action of the rating organization in refusing admittance to an insurer as a subscriber is justified, he shall make an order affirming its action.