Shocking moral ethics. Rather walk than fly with these cretins

Having booked return flights from Cape Town to Jhb, I made amendments to the booking online and then realised I had been charged an extra R3612 to do so when it stated on there site that there is a R300 charge to do so. I phone in to ask them to change it back to the original flights which they said they can do if there is availability but they cannot refund the extra charge. How on earth does a company justify this. The lady I dealt with giggled when I started to get a bit upset and said it was my fault for changing the booking. This company should not be in Buisness. Judging by all the 1 star ratings I am not the only one who has had a terrible experience. Avoid them at all costs.