318i s coupe L reg alram problem

[floydster]

Hi i have a bmw factory fitted alarm. the alarm set itself when i got out of the car yesterday which has never happened before. i have tried deactivating it with the fob but that didnt work ive changed the battery in the fob and that didnt work. there is a button on the actual key but that doesnt do anything either. unfortunatly when i got the car it didnt come with the owners manual or the key which u can use to turn the alarm off under the bonnet.

is there anyway i can deactivate the alarm using the ignition key?

please please help as i cant start the car because of the imobilizer.

thanks in advance

dan