Hold on to your seats

On my latest flight with Flysafair i I purchased my isle seat, ahead of time. I did not check agajn at check-in as I knew exactly what seat I bought. Boarding the plane I realised they assigned me to a middle seat. I immediately raised it with the flight staff who blamed it on me for not checking before the time. The i re-escaletd on Whatsapp and was again told that I "should have checked before boarding". I was then told it was "a computer ****ch". Discussing with other passengers i was told the same happened to them on the same flight. I am a computer engineer, this is not a computer glitch, it definitely looks like a deliberate effort by Flysafair to "re-arrange" passengers in a more prifitable way for Flysafair. This was further supported by the speed of refunding the amount paid for the seat. They probably have a button labelled "refund passenger who paid for seats".