Originally Posted by
Xandrios
An alternative method is that you could change the tickets (online) yourself, moving the flights to another day that has S class (or up) availability only. If you would have an acceptable alternative travel day that may work out. .
If you actually wait until S class becomes available on your original day of travel you can "change" the ticket online to go on the exact same flight but in the new booking class, with the usual fees as already mentioned. So, no need to change your travel day.