Had this problem when my Mondeo was broken into and the AA would not tell me how to fix it.... but the tow truck man that came out did..... On the driver,s side above the pedal,s...when you,ve removed carpet ect you should see a box with wire,s going to it ... this is the alarm module.... unplug the multi plug from this (its a pain to get to) then replace the plug after afew minute's.... this reset's your alarm plus immobiliser.
hope this help's
paul, April 2006