I recently (08/12) enjoyed my first CX flight. I had a C-Class Ticket JNB-HKG-FRA. The check-in agent in JNB was quite friendly and attached first-class tags to my bags. He then said he had a surprise for me an handed my F Class boarding passes.

I was quite surprised as I am not a Oneworld member and 'only' had my LX account in the record. I was even more surprised after boarding had completed and there were still about 15 seats empty in C. Can anybody explain this?