Webtoons is frankly a joke now. Maybe it was better a year or two ago but whatever is going on there is either a shady business and/or plain incompetence. I remember sending an E-mail asking for some help with something. About 2 months later, long after I had even forgotten my original message, I finally got a reply.
I have never seen such a large scale yet incompetent hosting site. The truth is you probably won't get anything. You can't trust Webtoons to do anything for you. The most I can say is, make sure you didn't accidentally put in the wrong username and password.
Like I said, if you're expecting Webtoons staff to do something you might be SOL.