Refused flight and refund

I was suppose to fly to Cape Town from East London today. King Shaka's Flysafair service was very slow. I arrived on time, checked-in as per their order that we need to check in on their counters even if we checked online. Stood in the looong queues, finally our bags göt taken and were given ticket print out. Went to the second gate, then on the boarding gate Im told to step aside, I step aside then I get anxious because I see time, I ask this gentleman why did you say I must step aside, he says there was an issue with your payment so step aside and you will be assisted. I stand there like a fool and the queue is getting empty. Only to be told by the other lady that there was an issue with payment of my bags, i must go to the ticket counters, I rush to the ticket counter as I see time is running out. Only for the lady at the ticket counter to tell me that the gates are closed so I must go back and fetch my kids. I ask her how, she just says go fetch your kids the flight left. I asked to get my money coz I booked on time and checked in on time but dela was on their side, she says I wont get a refund if I am not happy I should call a customer care Centre. Im furious, I need my money, this was not my fault, not to mention attitude of their staff and the lady refering to me as "That woman with glasses"