I was told at the ticket-hotline of the Ruhrtriennale that all tickets for Anna's concert in Bochum were sold out by 12:30 p.m. Let's hope for returns!
Thanks, Herbert, for the breaking news! The post has been updated.
I also tried to book by email, and the answer was: We were completely booked out after 30 minutes, and there is no waiting list. - Wow!