Every contract between a health maintenance organization and a participating provider shall be in writing and shall provide that, if the health maintenance organization fails to pay for health care services as set forth in the contract, the subscriber or enrollee will not be liable to the provider for any sum owed by the health maintenance organization. If the contract has not been reduced to writing or fails to contain the provision required by this section, the participating provider shall not collect or attempt to collect from the subscriber or enrollee sums owed by the health maintenance organization. No participating provider, or agent, trustee, or assignee of a participating provider, may maintain any action at law against a subscriber or enrollee to collect sums owed by the health maintenance organization.