Appalling delays in my flight

I really enjoy flying Kulula but today I have decided I won't be setting fool on their flights. I have an emergency to attend to at home and now my flight to durban (MN 603) has been delayed three times from 17:15 to 18:40 to 19:10 then to 20:45. Almost 4 ****** hours !!! When I got the first delay message I called the call centre and asked the agent to move me to another flight since I have to be in Durban ASAP, the agent said that i must pay R1200 extra to move to a British airways flight. But why ???? I got to the airport to find that people have been moved with no extra charge l. This has been the inconvenience of my life !!!! And I will never forget this day. I want my cash back.