If you would like to make a change to your booking, the first thing you need to do is check if a change can be made. First, you will want to go to My bookings.
You will be taken to a page that asks for your booking reference number and the email that you made your booking with. Enter this information and click Find my booking. You will be taken to a page with all of your booking information, where on the right hand side, you will see the following, if you are able to make a change to your booking:
If you do not see this, then unfortunately, an edit cannot be made to your booking.