For you who already use VPN Korea Server and still get ban, i'm sorry that i can't help you, because the ban it's pretty random to me. Already try over 10 times and loses 4 accounts at the process.
If you wondering what VPN i use,
OpenVPN for Android and
VPN Servers for OpenVPN. You need this 2 app and open VPN Servers.
I'm just waiting for global release, i don't want to get ban again just because it's different country.