Well Jens Peterssen and the Menze brothers are hiding behind a postbox company in the Seychelles - so from a legal point of view there is not much you can do. But their reputation is at stake here, as they are running other companies in Germany such as druckerpatronen.de / Jens Peterssen Internetdienstleistungen.

There are several tv shows in Germany (Akte / Wiso / Stern TV)  chasing scammers / fraudulent business owners trying to get customers money back. I would assume that they would be quite interested to investigate a topic connected to the hype around cryptos in general.