Provide assistance to your members who are having difficulty understanding why services are being denied. All HMOs have grievance procedures. Some of them are subject to DOL claims regulations. Regardless of specific legal requirements, the organization will be more responsive to requests for information about a particular problem if the question is coming from someone who can decide not to renew the contract rather than from an individual. If you do your job well you'll have an impact beyond your own plan.
Information is available when the market demands it.
You are the market.