Yes, reservations can be changed or modified through ‘Manage my Booking’. 

You can make changes to the  date and/or time of your travel, up to 2 hours before the scheduled departure time of your flight. Do note that changes to your booking will attract a fee per guest, per sector. Additionally, you will have to pay the difference in fare, if the new fare is greater than the ticketed fare.

However, if the new base fare is less than the ticketed base fare, the difference in amount will not be refunded.