Skywise cancelled flights and didn't refund money

On 13th October 2015 I booked my parents on the 09:00 flight from Cape Town to Johannesburg. I found out that Skywise was grounded upon arrival at the airport. So I booked them on another airline as skywise informed us that they don't know if they'll be able to fly again on the day. They also couldn't give alternative flights with a different airline. They promised a refund after 21 days as they couldn't provide the service. 21 WORKING days later I called and emailed, someone named Nqobi said that they will pay the refund and send proof of payment but it never happened. So basically I booked and paid for a flights, they didn't provide the service and are refusing to pay back the money. Can someone please help? How do I get my money back?