Keyfob failure,

[swifty62]

Advise please.message centre IPK,saying engine immobilsed,i have renewed the battery in the fob, but still won't unlock, lock, or start the engine, could it be the Transponder inside the fob, and if so, how do I go about getting it reprogrammed,it is an original key, and not a cheap fleabay one, and its the only key I have ever had with the car, its lucky it happened on my driveway,as usual its two steps forward, and one back,Grrrrrr regards Ian.