Poor service to elderly passangers. NO RESPECT

My Grandmother often flies from Cape Town to Johannesburg and back and used to only fly Mango. She refused to fly other airlines even though the fares were cheaper. So you can imagine how disappointed she was when she arrived IN TIME for her flight on Saturday, 3 August 2019 (From JHB to CT) - Flight number JE129 and was informed that she is not allowed to board the flight as she was standing in the wrong queue. She had to take a later flight and had to pay +/- R500 ekstra. She was standing in a line and a lady was walking saying something no one could understand, let alone my 80-year-old grandmother who has difficulty hearing in the first place. Then when she arrives at the gate, she is told she is in the wrong queue, they moved the CT passenger to another gate. When she got to the correct gate, she was informed that boarding has been closed and she must take a later flight. She had to make arrangements for someone to pick her up from CT Airport, and had to pay extra R500 for the later flight, which flight was delayed due to a late passenger!! I find this appalling to treat a very loyal pensioner this badly. She sat in the later flight for almost an hour! Why couldn't the same courtesy be extended to her for her first flight??? She was in tears, and shaken and so upset. And she cannot afford to pay extra for flights unnecessarily! She will NEVER fly mango again. very disappointed in the way Mango Airlines treat their elderly passengers!