The Nationwide flights don't work for us time-wise, but this info may help someone else:
Nationwide flt 746 departs JNB at 4:25 p.m., arriving CPT 6:35 p.m.
Nationwide flt 740 departs JNB at 6:20 p.m., arriving CPT 8:30 p.m.
Nationwide flt 806 departs JNB at 6:50 p.m., arriving CPT 9:00 p.m.
Economy was $105 per person one-way and business was $291.
Cheers!
Andrea