As the title says, how can I add on a seat belt on the middle of the rear seats of Grande Punto Abarth? I ask this because the Grande Punto Abarth does not have one from the factory built-in, neither it can be added on as an extra equipment (!) when ordering the car (when it was sold new), and at the same time the other Grande Puntos have it built in, even by extra equipment for the ones that don't have it built in...