There were no designated Avis parking spots at the Barcelona rental location; the car was parked in a regular garage spot. The rental was upgraded without notice, and we only found out upon collecting the car. Because the parking lot was far from the rental office and difficult to find, we didn't bother to go back and exchange it. A silver Opel parked next to our rental shadowed us, and when we stopped at a service area for less than ten minutes, the entire car was emptied. The car lock and windows were undamaged. We reported everything to the police and found witnesses, but it's hard to say if there was any foul play, and we had to bear the loss ourselves. When returning the car, the Avis staff were also very rude. After the incident, contacting the rental customer service provided only official responses. Overall, very unsatisfied and will not use them again.