Shocking and Misleading service

I booked 3 tickets from JHB to Durban paid just over R1000 per ticket. Just to find out I am on a Mango flight which is about R500 per ticket cheaper! Got to the boarding gate to find out the flight is delayed for more than a hour. SAA staff was very unhelpful and was told you now on a Mango flight altouh I paid the SAA flight, buy I do get a R50 meal voucher.