How can I get rid of an immobeliser from a Fiat cinquecento?

my mum recently brought a cheap run around Fiat cinquecento for £300:00 she has had it less than 5 days and the immobeliser is broke and she cant start the car. is it possible to get it over ridden or taken out. As the car was so cheap we really dont want to spend too much on this. but at the moment it is stuck on the drive and are getting really high quoted just to look at it, not even to do the work.