All modifications come with a cost.
You can modify your date and/or your destination Up to 72 hours prior to the date on which the flight is to take place. Click here for the modification costs.
If the price of your new flight is higher than the one of your original flight, you will have to pay the price difference in addition to the modification fee. If the price of your new flight is lower than the one of your original flight, there will be no refund. However, the modification fee remains unaltered.
A name modification also comes with a cost, see Can I modify a name in my booking?