I love Italy and I really don't want to write negative things about it, but I thought anyone hiring a car there needs to be aware of a not uncommon problem we came across below.
We hired a car from Rome airport in October last year, and 9 months later the same company charged our credit card for a further £95. I contacted the car hire desk in Rome airport and they confirmed that there should not have been any further charges. So the additional charge made by this company was fraudulent. I have been forced to cancel my credit card and take the matter up with my credit card company to get the money back. I still don't know whether I will get the money back.
BE AWARE that all car hire companies in Italy require you to leave a photocopy of your credit card when you hire, you cannot hire a car unless you allow them to do this. This means they keep your details on file and can use your details at a later date as they see fit. It also unfortunately means that your details can be used without your permission.
So my advice is to use a separate credit card with a limited balance, keep your car hire details for at least a year afterwards and check your credit card statements for unauthorised payments. I have also been taking photographs of the car and the mileage/fuel tank level with my mobile when we hand the car back so there can be no later dispute about charges on the car.
We have hired cars in Italy for the last two years at least 8 times a year and this is the first time it has happened, but I know from others that this is not an isolated incident. So just keep an eye on them and buon viaggio!