Change Flight Dates or Request a Voucher due to Corona Virus

No reply from Mango Flight after numerous emails & calls !! I have been calling and emailing Mango Flight since 20 March but all their phones are OFF and their emails just have an automatic reply. I wanted to change my Flight details due to the Corona Virus BUT Mango Flight is FALSELY advertising assistance on Free Flight Changes and Vouchers on their website. I already booked and paid my flight in Feb 2020 to travel from George to OR Tambo. In the automatic reply it stats that "Should you require prompt attention, require booking changes (minimum 2 hours prior to original published, scheduled departure times) or wish to effect a cancellation, kindly contact our Call Centre at ***. Alternatively, during flight operational times, you may consult our Guest Service Counters at all active airports within our network." How are you supposed to do this if ALL your Phone Lines are OFF and no reply on emails ?