Nonprofit health service plans are subject to Title 27 of this article. A corporation authorized under this subtitle that maintains or operates a nonprofit health service plan may not: deny a claim made under a contract, certificate, or policy of a nonprofit health service plan for an unfair or unfairly discriminatory reason; without just cause, require a person making a claim under a contract, certificate, or policy of a nonprofit health service plan to accept less than the amount due; or fail to notify in writing a subscriber or certificate holder of a nonprofit health service plan of a denial of a properly completed claim within 60 days after the plan receives the claim. If it appears to the Commissioner that an act or practice or proposed act or practice of a corporation authorized under this subtitle that maintains or operates a nonprofit health service plan is in violation of subsection (b) of this section or Title 27 of this article, the burden of persuasion is on the corporation to show that the act or practice or proposed act or practice is not in violation of subsection (b) of this section or Title 27 of this article.