Clio alarm

[acid drop]

Just bought a 92 Clio 1.4 RT off a mates dad 62000 miles full Renault service history. He bought it when 6 months old.It has a Renault alarm system fitted, not factory fitted but Renault aftermarket accessory. Was on the car when he bought it.I have found that it does not work, don't want to take it to main dealer as too costly. How do I check it out? Or where do I start?[?][?]