Kulula flights not being reimbursed or bookings with money avalable

I bought flight tickets to Cape Town last year February for my Grand Daughter’s 1st birthday on the 14th of April 2020. As you know Covid 19 happened. I received all my other reservations I made, a car rental and a holiday apartment for a week back from the other parties. Just not Kulula.. they promised that you can use that payment to fly with their airlines until end of November 2021. I then decided I will book a flight to George and back to O R Thambo for the long weekend. I phoned and explained and gave the Agent all the details of my flights to Cape Town. He then started the booking with both dates for flight to George and back to Johannesburg. Before he could do the booking I had to pay R1 298.98 before he could do the reservations. After I paid he said let’s do the 2nd booking for coming back… I nearly had a heart attack. The flight to George over R3 000??? I tried to cancel but he just refused and said I must have a “Great Day”. Then my husband got a doctors letter to say he has a chemo session on the date of the flight in any case. I tried to change the flight to flights to Cape Town but listen to this… the flights are less than what I would have paid for the flights to George but to change I must pay a fee of over R400??? When I refused he said my flight to George is still booked although I can’t use it. When I said I am going to write a report to Hello Peter. He said I must go ahead. I wrote how many e-mails to Customer Relations. I get read reports but NO REPLY… now I can’t understand that they are allowed to make money out of the Covid 19 pandemic although it was declared *******? They just carry on with business and nobody is doing something about it. Please help me to get a reply from them and the right to book flights before end of November 2021 without paying more!! Regards Lydia Weyer