Write to support@namubase.com. One person reads it, and you will get a reply within one business day (Korea time, Monday to Friday).
It helps if you include: the app name, what you clicked, what you expected, and what happened instead. A screenshot is enough.
Send the same address with "outage" in the subject. We reply first and investigate second, so you are not left guessing.
Apps sold through a marketplace are billed by that marketplace, so refunds follow their policy. Write to us anyway and we will point you to the right place.
Each app has its own privacy notice, linked from the app list.