After booking, you should have received a booking confirmation letter to the email address you indicated during booking.
Find the "Manage your booking" link in the email
The email must contain a blue link with the phrase “Manage your booking” or “Change your booking”. If you click on this link, you will be directed to your personal account.
In your personal account, click on the "Change dates" button
When you click on the "Change dates" button, a window will appear with the option to change the dates. But first, the system will check if the facility is available for the new dates. If so, you can do it by clicking "Ok". Please note that new dates may fall into a different price category, and the price may change.