What CAN (and SHOULD) you do in Germany?

If you are a German national and are worried about Yatedo abusing your data, you should contact the French Privacy Authority (CNIL - see related articles) and the German Authority.
Here are the details for the German Privacy Authority:

Der Bundesbeauftragte für den Datenschutz und die Informationsfreiheit
Husarenstraße 30 | D-53117 Bonn | Tel.: +49 (0)22899-7799-0
Fax: +49 (0)22899-7799-550
E-Mail: poststelle@bfdi.bund.de 
Internet: http://www.datenschutz.bund.de/

Anybody can contact them to indicate Data Privacy issues and request support. So start writing about your experience with Yatedo and how they are treating your private data.
Also, on their web site http://www.datenschutz.bund.de/ you can access a forum where you can discuss privacy information issues as well as more sources of Privacy information.

Remember: do not subscribe to YATEDO hoping to be able to delete your profile! They are a fraud and are only going to steal more information about you and your friends!