Different booking classes
I have a ticket to fly on 11 December LWO-MUC-FRA booked in K. When trying to change it to fly on 10 December (LWO-VIE-FRA), LH says it is 65 EUR (change fee) and 35 EUR (upfare from K to L, as K is not available). However, on both OS and LH webpages, I can easily book K fare for LWO-VIE-FRA.
Any thoughts why I can't rebook into K but can book a new ticket in K?
Thank you!