Mango AIr Line REFUND

Hi There, The airlines said we have a refund and gave us a voucher it expires this year Nov 2022. We are unable to get ahold of them. The is ridiculous. we cannot get them on the phone you on hold for 30 - 45 minutes every time. What can we do to get our money back?? We were emant to go on a cruise 2020, it was cancelled because of COVID. WE WANT OUR MONEY BACK