You need to reach out to the German dealer and ask them to change to dutch language (if it is available, not sure) on the update server. Then you need to update the tool. After this procedeur you should be able to select dutch in the language settings.

Note: This only applies if there already are an official dutch translation of the software.

 I have the same issue, bought mine fiew days ago, ordered english and dutch, but english and geman were delivered.
Waiting for answer from support ....

 support helped me out next day, via UpdateClient, working fine now thnx