Bad customer service

I had such a bad experience with this airline.They made me pay for a flight from East London to Johannesburg twice despite me having a confirmed ticket that has been paid for,that was on the 10th of September.I had since contacted the customer service and they promised to pay me back but since then I haven’t been refunded my money.They only respond when I write to them and the last time was the 11th of October after I sent them an email and they haven’t contacted me or refund my money