Kulula will take your money for a flight and even though you paid for it and are on time

I bought a return flight from JHB to CPT which is 3 months from now - cost me just less than R2000. To change one flight to a week earlier they want to charge me another R1449!!!! Its cheaper to buy a new flight but no no, they will CANCEL my return flight and keep ALL THE MONEY ! Literally paying for service I wont receive even if I'm on time for the flight I paid for!!! You get you money, how greedy do you have to be!