Unprofessional behavior

I have a booking with mango for a return flight from George to OR Tambo on 10/08/2020. Our flight to PE on 06/08/2020 was cancelled due to travel restrictions and we got a voucher. Problem is I’m now struggling to get a voucher for the return flight from George to Johannesburg. I have phoned and emailed mango numerous times with no assistance. I hold for over 20 min only for the call to die. I was advised to email Ronald Cloete who isn’t getting back to me,neither is the voucher email. This is really unprofessional. Someone needs to send my voucher ASAP to give me my money back!