We have rented there several times and everything was ok, except last time. We specifically asked for a diesel car, as we always do, and got told we need to pay extra. So far, so good. Extras cost additional.
Later at the parking lot we got a gasoline car and asked for the Diesel. The staff from the parking lot called with the office in the airport and they said we didn't want diesel, we got a higher category. Later we where also informed that they don't have any diesel car in this category.
Also this was not a language problem since my girlfriend is a local.
Apart from this, the staff was friendly and fast.