SAFAIR refusing to refund their customers due to Corona virus

I booked SAFAIR to fly to George on 4 April 2020. Now I had to cancel the trip as we are in a State Of Disaster as declared by the president and I have to comply with cancelling all domestic travel. Safair are refusing to provide a refund - instead they are giving a 6 months voucher. I want a refund not a voucher!