If you can no longer go on your trip, or if the owner has informed you of an issue with the vehicle preventing your departure, you can cancel the booking directly from your profile.
To cancel a booking and ask for a reimbursement, you must log on to your profile and click on My Trips.
Click on Review my Booking for the concerned hire, and click on Cancel.
Follow the steps highlighted depending on the reason for the cancellation. Details on the Cancellation Terms are available on the article What happens in case of cancellation?.
If you have subscribed to the cancellation insurance, and you wish to find out the procedure to follow, click here.