This section does not apply to a physician or group of physicians who: Have exclusive contracts with a health maintenance organization; Treat only the patients of the health maintenance organization; and Agree to accept full assignment for covered services rendered. If a physician is engaged in the private practice of medicine in this State, the physician shall display a notice written in English that is plainly visible to patients in the office of the physician concerning whether the physician: Is a participating physician under the Medicare program and, therefore, accepts assignment for all Medicare claims; Accepts Medicare assignment on a case-by-case basis; or Does not accept Medicare assignment in any case.