Cancelled flights - No refunds

I recently booked a flight on Fly Africa from Harare to Victoria Falls. The flight got cancelled 2 weeks after the booking was made. I am only being offered a voucher which I can use for future flights (within 6 months). As I am not planning to travel in that area again soon the voucher will be useless. The call center agents are useless. They just say its policy to only give a voucher and a cash refund is not possible. Surely this is paramount to steeling?