1. Did you purchase the flight directly from Saudia or through a travel agent or third-party website (on line travel agent)?

2. For schedule changes, the good EC261 rights apply when the changes are made within two weeks of departure. Otherwise, your best (required) option may be to take a full refund (not just future flight credits) and purchase a new ticket that you like, although it's likely to be more expensive.

3. It's odd that Saudia would drop all service to both Vienna and Seoul. Have you verified this? Are there perhaps (Saudia or partner) flights that connect somewhere other than Jeddah? Have you looked for connections through Riyadh for example?