You can change your registration through the "MY RESERVATIONS" section of the website, as long as:
- DO NOT change the brand and model of it
- You have NOT travelled any of the trips of the booking
In this case it will not imply any additional cost. If the change implies a change of model and brand, there will be a repricing and you will not be able to manage it independently.
You can modify it at any time before your departure, once you have completed one of the routes you will not be able to modify it.