Hopefully i can help..
Is this fairly recent fitment or one thats been on the car a while?
It was an original fitment from 1993.
Very much like a large metal fuse that slots into the immobiliser.
Ok so its genuine peugeot electronic immobiliser...some people fit better aftermarket types hence why I asked and would no doubt get another jack for that if a recent device - I have checked the parts database and it doesn't mention any parts for that - so I would assume they have stopped listing that or any parts for it a long time ago - If that's a genuine fitments then it could be quite difficult to get another jack for that device - maybe worth trying the dealer anyway if prefered and see if they can get another jack for it using the vin number they will tell you either way..it would have to match the immobiliser system on the car so you cant just get another jack as it wouldn't work without some sort of programming..From previous experience ive seen a lot of these cause all manner of problems especially the jack itself wearing out over time and not allowing the immobiliser to shut down and seen a lot get bypassed for that very reason and or a much better fitments installed ie:- Cat2 immobiliser thatcham/toad sterling devices is usually the most common for fitments on older vehicles.and much more reliable..You could try this site and see if they can help http://www.abacuscaralarms.co.uk/ I do hope this helps