Mango Airlines robbing people their hard earned money

My 2 friends and I were supposed to go on a cruise in April 2020 but due to the Covid pandemic it was postponed to January 2021. Then it was later canceled because no one knows when this will blow over. We booked Mango flight tickets. I called them and explained everything, they sent me a voucher which was valid for 24 months. I told them to refund us because our cruise has been canceled. They told me their tickets are non-refundable. This situation is beyond everyone's control. This is day light *******.