Sec. 12. An insurer shall establish and maintain an external grievance procedure for the resolution of external grievances regarding the following:
(1) The following determinations made by the insurer or an agent of the insurer regarding a service proposed by the treating health care provider:
(A) An adverse determination of appropriateness.
(B) An adverse determination of medical necessity.
(C) A determination that a proposed service is experimental or investigational.
(D) A denial of coverage based on a waiver described in IC 27-8-5-2.5(e) (expired July 1, 2007, and removed) or IC 27-8-5-19.2 (expired July 1, 2007, and repealed).
(2) The insurer's decision to rescind an accident and sickness insurance policy.