Just a quick word to say that the Xantia will deadlock and alarm without the plip, when you turn the key in the door to lock, hold it turned for a couple of seconds and you will hear the deadlocks activate, this also should put the alarm into action.
Both the Mk1 Xantia Owners manuals I have here (1994 & 1997 MY) state that while deadlocking can be done with key or plip the alarm can only be set using the plip.
