FlySafair nowhere to be found....

I have made a booking with FlySafair. I have received an email about a change to my flights by FlySafair. Shortly after this change to my flight I tested positive for Covid and had to cancel my flight (medical certificate available). According to my booking I should have received a full refund (voucher for this booking) - but that was not the case and I was issued with a voucher R600 short of the full refund. I have also sent an email to FlySafair - no response. I have tried to contact them via WhatsApp - no response, I even tried Telegram - the start of the conversation on Telegram is a message that this platform is unattended by an agent from Flysafair. It is impossible to get hold of an agent telephonically as there is no option to speak to one and all messages are merely automated. This is absolutely shocking service.