Rude customer agent

On the 4th of December I was on standby for a flight to Durban. The first agent I spoke to was not very friendly and looked I was a bother. I made a mistake when I made a booking , so I had also spoken to another of the ladies there so that I could rectify the durban -johannesburg ticket and had told her that I would change it once I knew if I was going to get a space on the jbg-durb flight. So when I found space I wanted to pay for both changes and unfortunately the agent was off with me saying that she couldnt help me anymore since she had offered to change my ticket whilst i was waiting for the standby. I ended up pay lots of money for both changes and felyt it was a ******* and will never use mango for me or my clients ever again. What reaklky riled me was that instead of paying about R850 or something for durbs-jbg I ended up paying R1480 or something due to her unwillingness to help me. This was a very bad experience for me and will fly on a more expensive carrier than use mango