I have immediately tried to cancel my subscription but it was permanently blocked with the message "Falscher Bestätigungscode.." That looks like an abo trap!

Avoid is right. Avoid this ad blocker like the plague. We added this and soon it was saying I needed to pay. Then they put a pay reminder in your browser that is very hard to remove. You have to go into your apps to remove this whole program that tried to mess with your computer. Pass.