Worst customer service

I booked a flight from East London to Cape Town online and the print out had no check in min time. The flight was scheduled for 19h40 I arrived for check in at 19h10 I was told I am 5 mins late for check in and can only fly tomorrow morning if I make another booking. I then told the lady that was helping me that there was nothing written on my booking about checking in time, and she asked the see the flight print out. She asked me if I had flown before and who made the booking. I rep**** and said I had flown before and o made my own booking. Her response was clearly I had no idea and flights. I told her that I had to be in Cape Town for an interview tomorrow morning by 08h00 could she not help me or call her supervisor to assist me in anyway. She then said that she is the one that makes the decision if I’m flying or not and I was not going anywhere I better go and book the 08.00 express flight for tomorrow morning. There was another gentlemen behind me taking the same flight and she also said to him sir you better go book another flight if you know what’s good for you. The way she handled the whole situation was frustrating. She could have symphathised with us or called her supervisor to show that she was legit in her decision. I don’t remember her name but she is an African lady with short tinted brown hair at the East London airport