A hospital cannot recover more for its emergency care of patients injured in car accidents than the amounts it has agreed with the patients’ medical insurers to charge for those services. Here, the hospital tried to collect more by requiring the patients to sign conditions of admissions that contained assignments of the patients’ underinsured motorist coverage and medical benefits coverage under the auto policies. This decision holds that the assignment was void as prohibited by state statute. Even as to patients who did not have health insurance or with whose insurers the hospital had no agreement, the assignment of underinsured motorist benefits was unconscionable and unenforceable, though the assignment of medical benefits coverage might be enforceable.