Mango, Corona, refund request, no one comes back to me for 3 days now.

I have now tried to contact Mango via email 3x days in a row. I have called them on ***, yet no response. I have to hold on for an hour and longer at a time, if you are lucky to get through at all. I am now out of airtime. I have booked 4x return tickets on 22/01/2020 dated for 12 April 2020 and return 22 April 2020. With the lockdown of 21 Days I cannot take leave this year. I am not sure what will happen next year as I already have a potential overseas trip and can only take 20 days leave per year. How can I get a FULL REFUND of my air tickets PLEASE? I cannot take vouchers and I cannot postpone my holiday as I have NO MORE days for 2020 due to the lockdown. PLEASE is there ANYONE at Mango who is willing to assist me? Thank you, Wilma