Hi I've just bought a Skoda fabia 1.6tdi se as soon as I take the key out the ignition the alarm goes off I've got to lock the door twice with the key and after about 30 seconds the alarm goes off I then have to press the unlock button and then the lock button to stop it sounding it's the same when I unlock it I've got to unlock with key soon as I do that the alarm goes off until I put the key in the ignition any ideas on how to fix this would be most welcome thanks