Cancelled flight and did not refund me

I booked a flight from Pietermaritzburg to JHB on the 29 Nov 2015. I got an email a few days before saying that the flight is cancelled. I had to book a flight with Kulula to deal with this cancellation. I called Fly Go-Air and they said I will get a refund after I send my bank account details. I send my bank account details on the 23rd of December and have not received a refund as yet. I call the airline and there is an automated response saying the operators cannot take any calls and I should leave a voice message. Once the automated response is complete, I am notified that the airline cant take any voicemails. I emailed the airline again today and received no response. I have a feeling they wont refund and I am very concerned!!!! This airline is extremely unprofessional.