I had a similar level of disatisfaction with an accident repair many years ago and I marked up my car in a similar way to show just how many faults there were
The way it was resolved was to get a troubleshooter / show painter from the paint supplier (Sikkens if I remember correctly) to actually respray the front of the car and the end result was perfect both in terms of paint application and colour match. Maybe FIAT can arrange for a similar professional to fix your car.