Received a dirty car with half-empty fuel, staff don't-care at all

We reserved a Audi A3 but got a Mini Cooper( same class according to the car rental angency but we prefer an Audi A3, no big deal though), the car was absolutely disgusting and we're too busy learning everything about the car before drive away from their Rome airport garage that we forgot to check the fuel level, a few minute after we checked out from the garage we saw that the fuel was only half but the paper stated it was full so we had to return to the garage and ask the staff, he wrote sth casually on the paper and walked away with zero interest in listening to our complain about the dirty car. When we returned the car in Ancona the guy there told us that's what happens at their Rome airport branch quite often, guess they're either understaffed or just have no desire keeping their customer! Btw on my confirmation with EasyRentCars it states clearly that the price quote includes one-way-return but when we picked up the car Maggiore still added a charge we can't remember why but we never buy any add-ons when rent cars, one driver/deny all insurance coz our credit card covers it/same fuel level/no gps needed....we needed nothing extra, now Amex is investigating the extra charge for us.