Rented a car from SIXT in Girona just outside the train station for our 10 day tour of the area. Easy to find their office which is within easy walking distance of a few hotels if you are overnighting after a long train journey. Staff are very friendly and helpful. You collect and drop off the car in a nearby car park (2 mins walk). Again, very easy and close to the station. Minimal fuss and a good experience - SIXT did exactly as I expected. Prices were competitive with all the other big car rental places and SIXT seemed to have a good choice.
A bit of a sales push for insurance protection etc but to be expected. A word of advice, if you are going to be late collecting your vehicle, LET THEM KNOW IN ADVANCE! Read the small print on the agreement… another couple in the office hadn’t done this and arrived late to collect their car only to find SIXT had cancelled their reservation. All resolved in the end I believe (my French isn’t that good anymore!) but a simple phone call would have avoided a lot of stress (and swearing)!