Delayed 5 hours for a local flight

I was booked for a flight to depart at 17.00 .Flight delayed to 22.20. I called the call centre to assist to change my departure time and was told ok can move u to departure O R Tambo at 19 15 .Get to the counter still waiting for an email from mango with the changes and then was told unfortunately they couldn't have moved ur flight coz they were having issues with flights and moved all flights to smaller aircrafts like WDF .That is not the clients problem if mango decides to go smaller then they shud just shut down.