Your ticket was created 2018-01-27 15:13:58
Your ticket must be answered in 24 hours and it was answered: 2018-01-28 12:42:57
So after this must start 12 hours when supports must change your class, but 28 Jan is Sunday.
http://l2classic.club/forum/topic/7439-class-change/ From the moment of the answer, Class change will be made withing 12 hours. Class changes will not be made on Sundays!
So this 12 hours starting from Monday morning when supports start they work and they start work from: http://l2classic.club/forum/topic/3510-how-to-submit-a-ticket-to-support-center/ Support Center work time - 10:00 - 22:00 CET
So your class change must be made in 12 hours after 10 CET.
So your class change wasn't delayed or anything, it's still making in time.