I wonder what the difference in his cost was flying DL from ATL>JNB>ATL, instead of taking all that extra time flying VS from ATL>LHR>JNB>LHR>ATL? They must need the VS miles instead of DLs perhaps? Then again it also depends how long of a stopover on the outbound leg that they are taking! Would a stopover at LHR still be bookable on the same PNR if the stopover is more than a certain # of hours?