Kulula *****ing my money!

I have booked a return ticket from Jhb to Cape Town for my daughter who is a student in Pta. She could get away sooner and as changing the kulula ticket was more expensive tha n a new Safair ticket, I booked a new ticket on Safair to fly to Cape Town. I then tried to change the origonal ticket from Jhb to CT to a dat alter in the year. The website would not allow me to book a ticket for a date after her original Return date. Maybe this was fortunate, as I then called the call center. Changing the ticket to a date in September this year was going to cost me more than R800. Again this is more than a new Safair ticket. Fortunate y the agent then inform me that if I do not cancel the booked ticket form Jhb to CT her return ticket will also be cancelled and I will have to pay Kulula money to rebook it!! I cannot believe this. Surely if I have booked and paid for a ticket it is mine, if I do not show that empty seat is still mine and I lose the money. How can Kulula then cancel my other seat as well and charge me more money to reboook it! This is *****!