why book SAA but end up flying Mango

<p>I booked SAA flights one on the 27th from JHB to CPT and on the 2nd of May from CPT to JHB for my partner via travelstart with Reference numbers ZA ********** 1 and ZA ********** 7. I was so upset when he told me that he boarded Mango instead of SAA, why? What is happening? SAA is my preferred airline and not the others, well only because I valued the service offered but seems I got it all wrong this time, someone cares to explain to me what happened or why that happened?</p>