Good mornign, matthias_bloenni.
Based on the information you've provided, the best course of action would be to contact our support team outside of the Community. They'll be able to verify your account details in a secure setting, as well as view your screen to better assist you. You can reach them by following one of these methods:
Schedule a Callback or start a Chat: click (?)Help in the upper right > type and enter "Contact support" into the QB Assistant > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat.
If you have any other questions, feel free to reach out here.