For the record it was 2 x 2,500 euro business class tickets. Certainly not a throw away job
Well yes, they may well have been priced up at 2.5k EUR for the return ATH-JNB-ATH. Whilst the one-way ATH-JNB might well have been a fair bit higher than 2.5k.
Hence why some people still like to risk throwaway ticketing and not fly the last leg because its cheaper to buy the return ticket and forget about the last leg.... the airline will always have the last laugh though, they can do an awful lot of data mining very quickly on their databases to pick out suspicious stuff.
Hence good luck with the airline, but I wouldn't hold your breath.