No Refund

We booked & paid for 2 Airline tickets from Jhb to Harare for 2nd November 2015. On 1 November Fly Africa Sent an Sms cancelling the flight. We lost a whole week of our leave trying to contact them via phone with no reply & no reply to my numerous emails. We had to book another airline. Eventually Fly Africa Sent an email stating they would refund our money within 30 to 40 working days & asked for our bank details which I submitted. To-date we have had no refund nor any response to my numerous e-mails. Please advise what I can do about this terrible service & non refund from Fly Africa? Thank you.