The mutual insurer may, by action of not less than three-fourths of its board of directors, abandon or amend the plan of reorganization at any time before the effective date. No amendment made after the public hearing required by subsection d. of section 4 of this act shall change the plan in a manner which the commissioner determines is materially disadvantageous to any of the policyholders unless a further public hearing is held on the plan as amended.
N.J.S. § 17:17C-11