Worst flight

I'm very disappointed with this airline. I booked a return tickets for me and my 2 children on black Friday, to travel on Tuesday the 12th of December 2023 and to return on the 13th of January 2023. I got at the airport 25 minutes to 6 because of transport, I got there they said boarding is done that I should go and change for the next flight I got to the ticket selling office the lady told me it will cost me a lot of money to change the time I asked how much she said over R11000 I mean these are the tickets that I bought for about R5500. I told her I couldn't afford over R11000 she said there's nothing she could then closed the office and left, now I'm there stranded with my children crying then, my husband couldn't take it seeing the way they were crying so he bought other tickets which were cheaper on lift with us knowing that we'll still use the same tickets for return. When I got to Joburg I checked the tickets with saa the same day they were R5700 for all of us, so call the call centre and told that I should still pay the R11000 if I have to use the same ticket to return to Cape Town, now I'm stranded, I don't have money to return home and my child have to go home in January for school. This ticket seller didn't even explain to me that I could just add on for the next flight which was R5700. I had to go on internet to find out that I could have add the money and board the next flight. This is day light *******. Had I known I would never have booked with them I won't advise anyone else to use them