You will need to go to the fiat dealer and speak to them, you will usually have to pay for them to order the code in, and most likely prove ownership of the car before they would do so.

There are some machines that can read the code from the ECU, but these machines cost about £4000 and the only people who have them are either criminals looking to steal cars, or automotive locksmiths who will do it for you if you are paying them to make you a new key to use on the vehicle.