My immobiliser key stopped working all of a sudden, i opened the car and left it but when i came back to start the car my key wouldn't work. Its a Renault Megane Scenic Auto, 1998. the doors are unlocked but when i open the door, the alarm goes off and i cannot start the car. I took the key to the dealer and was told that there was no signal and therefore would have to buy a new key which would cost me around �130. If anybody can help please let me know.