2006 M35 Proximity Fob stopped working...

MadDog76

All features worked one day....next day none of the buttons worked, although the car will start by plugging the fob into the slot under the steering wheel. Changed fob battery, but still no go. What would cause the proximity features to suddenly drop of the map?? Do I now have to pay one arm for a reprogram...or (gulp) both arms for a new fob key??