Changes are coming to "private fee for service" plans, a fast-growing and controversial type of Medicare coverage. Private fee for service plans are a type of privately-run Medicare alternative known as Medicare Advantage. Like other Advantage plans, PFFS plans wrap coverage of physician and hospital services in one package, sometimes with additional benefits such as vision care. But unlike other Advantage plans, they don't have a network of doctors and hospitals beyond which coverage may be limited. That has been a big selling point to beneficiaries, but that aspect is changing.