I agree with the previous post: STAY AWAY FROM SIXT NAPLES AIRPORT.
We arrived late for our car by about 5 hours, they told us that we missed our reservation...huh? They said they had no other cars, so we decided to go with another company as Federica and Luca, the Sixt employees, did not seem they were going to help (should have taken the hint...)
As we waited for the Shuttle bus to go to the parking lot with the other car rental companies we unintentionally stepped into the Sixt parking lot, they had not one but at least 3 of the car I had booked. Our "friend" Luca showed up and I asked him about those cars, he told us they needed to clean them before they could offer them to us, to come back in one hour.
After spending an hour looking at other options, my booking with Sixt was still a cheaper price so we went back to Luca and Federica, who were really surprised we were back...in the end no car from Sixt as Federica told Luca in italian to "screw me" and offer me a bigger car for which I would have to pay the difference...I got annoyed and asked for their manager, they said they had no manager... So I asked for their names to make a complaint but they refused to show me their badge so I had to settle for a little trick to get both their names.
At least this was the worse part of the vacation so it could only get better from that point. read more