No payments shall be made by a nonstock corporation to a person included in a subscription contract unless the payment is for breach of contract or for contractually included costs incurred by that person or for services received by that person and rendered by a nonparticipating hospital or nonparticipating health care provider. In no case shall that person be denied the right to assign his rights to benefits, except that denial may be made where the benefit is eighty percent of covered charges or greater.