Delayed Flight

I went into King Shaka airport to the SAA desk and asked if I could move my flight earlier. I paid a fee to move my flight from one in the early evening to a 13:00 flight SA550 on 29th September 2017. The flight was then delayed and only took off at 15:15. Why would SAA staff take money to book you onto an earlier flight when they should have some kind of an idea or information that this flight would be delayed? Really bad service and excuse after excuse from the pilot about why this is not their fault and the problem lies with someone else. Really shocked at the inability to take overall responsibility and really shocked that they would take my money like that without saying anything.