We arrived just before New Years with a reservation at a different car rental company, starting with E. We'd made the reservation four months ahead only to find they'd cancelled our reservation (though I confirmed the night before) and rented our car to someone else. There were absolutely no cars in Colonia during the holiday until Dario found one for us, then found one that would fit all five of us for the next day. They were dogged and creative in their problem-solving, and really really nice to interact with. Honestly--everyone at Sixt gave me faith again in what devoted employees look like, and how a well-run company responds to a challenge, when in fact they owed us nothing. I'm a convert after years of renting from the same big companies. Thank you Dario and crew!