Do you have Mobile key?
If you use Mobile key, you can look up your username on OP's mobile app (Customer info – Settings). If you can't look up your username or have forgotten your password, replace your user ID.
Replacing an OP user ID by using user identifiers issued by another bank is currently not possible
If you've forgotten your user ID, you can get a new user ID by visiting an OP cooperative bank branch. Bring a valid passport or identity card with you.