I also had a bad experience with sixt, in Berlin airport. After booking a small car and asking for automatic shift two weeks in advance, arrived at the counter and was informed there were no automatic shifts in the car class I booked. They would need to upgrade me for an additional 150 euros plus fees. I think this is called bait and switch in AMERICA and this is not allowed to go on for very long. This was the first rental at sixt and will most likely be the last rental at sixt for me.