Question for DONG YANG EXPRESS FERRY CO. Ltd

I understand Dongyang Expres Ferry is operating the passenger ferry service between Busan and Jeju. I have tried but not able to access your internet booking system for ferry service from Jeju to Busan. My questions are
1. What is the cost of per passenger if I want a bunk bed room for six person? I am travelling with my family.
2. How to book by internet?

My name is Lee Kham Kuan. Most likely the ferry trip will be on 17th Dec evening from Jeju to Busan.