Double charge

We booked tickets on 10/05/2015 to fly to Cape Town from Jhb. Somehow they double charged us and the amount of R2776.90 went off our account twice. I called the call centre on 22/05/2015 to correct the mistake, they picked up that the amount did go of twice and said the mistake is rectified and that the amount of R2776.90 will be refunded and reflect in my account within 21 days. That did not happen. I phone again early July, the person told me he will investigate the problem and phone me back - still havent phoned back!!! Is this how they make their money?? Double charge and conveniently don't pay back??? Very poor service. Will not be flying with them again!!