If payment has not yet been made, booking requests can be modified from within your account under My Trips. Once payment has been made and a booking is considered booked, modifications can not longer be made to the dates or payment amount. If you need to book a longer stay, you can always submit a new booking request. If the stay is going to be shorter than expected or the dates have changed, you will need to cancel your current reservation and submit a new booking request for the altered dates. If this is your situation, we recommend contacting the host and informing them of changes prior to completing the before mentioned steps.