I saw in other forums that there were a number of more people out there who received similar results and were equally surprised.
As I heard that the PMI had some issues with previous exam change-overs, I decided to double-check with PMI customer support whether I have really failed or at least to point out to them that there exam report does not really make sense anymore.
Last night I received a mail from PMI apologising and telling me that I have now passed my exam. According to this mail "An error in exam processing occurred because exams were originally scored by an erroneous scoring process so that some candidates’ pass/fail result was calculated incorrectly. Due to this vendor processing error, some candidates received incorrect exam reports. The error has now been corrected."
I still can't get my corrected exam report from the PMI website, even though the mail states that it should be available there. I hope/think this is just a technical glitch.
So this is obviously very good news and I'm very happy that I don't have to repeat the exam!
Thank you all for you encouraging words!