In October 2012 I suffered my worst car rental experience ever. It was with Goldcar - a Spanish company new to Italy and so there is not much feed back yet. But boy, I've found a huge number of complaints about them in Spain.
Their staff at Bologna Airport are rude, unhelpful and basically thieves! They hold you at the desk for half an hour selling extra insurance for €125 (which still does not cover glass, wheels, mirrors, interior etc), you have to pay an exorbitant price for a tank of fuel (the tank wasn't even full) and there is no refund for remaining fuel on return plus they charge an extra supplement for diesel (when diesel in Italy is cheaper than petrol).
Goldcar's car park is at East Terminal which is a long walk from the rental desk. I'm partially disabled and they would not give me any assistance.
On return they would not believe that I did not take out the extra rip-off insurance and wanted to search my bag for a document they insisted I was hiding! I then had to wait while one of them went to check the car for damage - eventually he phoned in to say the car was ok - undamaged and clean. Despite this, I later found an extra charge of €32 had been made to my card for no reason.
They are absolute rogues and next time at Bologna (November) I'm going to demand an explanation - although I doubt I'll get anywhere.