Dear Claus,
thank you very much for your detailed response with a lot of interesting insight!
So far, still no news regarding my ticket. I could now easily book a similar ticket on the same flight with another dealer. However, I'm a bit worried that the airline might not like me being twice on their flight, if they even ever got a reservation at all. They are also not responding to my inquiries.
Regarding the company Airprojects.com, this seems to me like a zombie corporation. Most of the automatic systems (website, answering machine) still work, but none of the payment or booking systems.