Flight cancelled, did not receive refund

I booked a flight from Pietermaritzburg to Johannesburg for Dec 18th 2015. Eleven days before my flight, I received an email from Flygoair's IT Department saying that the all flights for that route had been had been suspended. In the email it was requested that passengers supply their banking details for a full refund. I rep**** promptly with all of the relevant details including proof of payment. Since then, I have not received any refund or further communication from Flyoair. I have tried telephoning the Johannesburg and Pietermaritzburg branches multiple times but the lines are always engaged or busy. It would be greatly appreciated if Flygoair could honour their promise to their customers and refund the flights that were cancelled.