The regulations of the German civil law book are valid.

Agreement on jurisdiction:

"Munich is the place of jurisdiction if the customer is a merchant for all disputes."

Dispute settlement
The European Commission provides a platform for
online dispute resolution (OS).
The platform can be found 
at:
https://ec.europa.eu/consumers/odr/
main/index.cfm?event=main.home.chooseLanguage

Consumer dispute resolution law
We are not prepared and obliged to participate 
in dispute settlement proceedings before a consumer 
arbitration board.