The fastest way is to talk with the congstar service team. When I had the same problem, I talked online on the chat room and in 20 minutes they had my new Sim card ordered! Next day came by post.
Yes the support team on chat helped me!!! Danke
Hallo congstar team,
Ich habe das gleiche Problem.
Ich brauche die Nano SIM, mein Vertrag lässt jedoch keine Bestellung zu...