Since there is no way to contact adobe (at least not to find quickly), here a warning for "new" users:
There are users who message you as "adobe customer service". Instead of really helping you, they try to get your serial number. Please don't be stupid and tell anyone!
Does anyone know, where I can report these users?
You can report it by clicking "Report":
Thank you! I was looking at the user's profile for a button, so I didn't notice this in th message.