Did you know that above every Medicare plan is the judicial oversight of an Administrative Law Judge (ALJ)? When the plan makes an adverse coverage decision, first you should appeal to their better judgment. If you are unsuccessful, then you can go over their heads and appeal to the ALJ.
But wait, there is more. If you are unsuccessful before the ALJ, then go even higher to the Medicare Appeals Council (MAC). Be aware, however, that at this level the process becomes a matter of litigation and all that entails time and money. Nevertheless, litigation is sometimes a necessary evil to pursue necessary care (and justice).
You may never need to challenge a denial of coverage. In case you do, however, it is best to be prepared and that means being well-informed regarding your rights.