I don`t know does this happens frequently, but mine AdWords penalty is lifted. I was banned because i entered wrong code for promotional discount.. After 5 mails where i demanded from them to lift the penalty, they did it.. Mail is not in english language, but i can add Gtranslate version if needed. Regads all, and hoping to help to fellow IM-s.
I think your wrong code attempts seems spam to google. So they banned your account and gave penalty .
Account gets banned not because of entering wrong promotional code, its because of how the ads has been created or how they have been using their keywords...