Section 16. It shall be unlawful for any person, group of persons, or entity except an insurer or sponsor of an insured legal services plan or a membership legal services plan, to establish, underwrite, operate or offer to sell a legal services plan, except in conformity with the provisions of this chapter; provided, however, that the provisions of this chapter shall not apply to a labor organization providing legal services to its members and their dependents nor to legal fee reimbursement services provided by an automobile club in conformity with the provisions of chapter one hundred and seventy-four B.