Worst rebooking experience ever

The worst experience of my life and the call agents are rude as well. I booked their sunbird flight, and I had to put it on hold. I am travelling again, and the flight is cheaper than my originally paid amount, but I still have to pay an additional R561 regardless of the fact that I already paid twice the current price. Because its on hold "I can't rebook it myself" I want to add a back - I can't do that either - apparently, you need to pay per KG, and apparently, it won't change. Even if I can, I will just be charged at the airport. They are practically *****ing money and pulling the rug. I guess this is what I get for changing flights from British Airways; even FlySafair is better with their rebooking and baggage policies. This is is all BS.