unsatisfied airline customer

i am completely offended and disgusted at the attitude of mango airlines. my flight was scheduled for 19:15pm on flight je284, when i arrive at the airport by 18:15pm to check in,i am told the aircraft had an issue at cpt at 9am and that a smaller aircraft was used to accomodate for the same amount of people...that is ridiculous. firstly how can mango get a smaller aircraft when they are well aware of the number of passengers from Dbn to Jhb on je284...and secondly they had at least 8 hours to sought the problem out. I was not at least notified by the airline that there has been an issue with the plane, and yet it happened 8 hours prior to the flight. it would have avoided me from coming to the airport early to check in and sit and wait til 10pm to fly back home to Jhb. Then again the lady at the check in counter has advised that the flight was overbooked, so what story am i suppose to believe. they wait for us to get there to lie to us at check in and then they book us the latest flight there was. i had to drive in jhb at 1130pm as single female for almost an hour to get home. how will i be reinbursed for the inconvenience and impact on my safety getting home from the airport.