Account wegen EULA Verstoß gesperrt

Hallo everybody, I need help. The account of my son was banned, because of the EULA Rules. We didnt know, which mistake we had done. My son is a member of a really nice team and wants to play the game. Every time when we try to install the game new, it isnt possible. Has anyone an idea? Do we need a new mobilephone or a new telephonenumber? Greetings Smaragd