Poor notification procedures

I had booked a flight on Mango airline as I had recently also joined SAA voyager. I am a regular flyer (1 - 2 a month) as travelling is part of what I do on a regular basis. My regular airline of choice is Safair. I had checked in online on the 14 January and all was fine with Mango thus far. <br> <br> I arrived at the airport around 10:20 and made my way to the boarding gate as displayed on the board - G6. This showed gate 6 and also showed delayed flight JE538 at gate 6. I then made myself comfortable at gate 6 and awaited call for boarding. At round 11:29 whilst waiting for the delayed plane, I received a phone call. At around 11:30 there was a lady who requested if I am on the Joburg flight and I said yes. She then exclaimed that I had just missed my flight and that boarding was moved to gate 5. I stated it still shows delayed at gate 6 and pointed to the screen. I did not hear a call out for my name, as gate 6 is also partitioned off partially with a shopfront door. <br> <br> Please note all screens continued to show gate 6 and NOT 5. I have the photos showing same taken at 11:40?! I have never missed a flight in my life and my experience with Mango was exceptionally poor, to say the leas