Failure to resolve a client's issues

In Short: I was first of all asked to purchase another bag at King Shaka Airport by a manager as well as threatened because I complained that being overweight by 2kg and then told I couldn't board the plane because I was 2 kg overweight was unnecessary. I also had milk spilt on my by the air stewardess. When I complained about this to Mango I was basically told we look after our own and we don't care about your complaint. All I want to know is what questions was asked by Mango's Managers to investigate these incidents and why they failed to train their staff and manager at King Shaka Airport when their staff at O.R. Tambo can deal with their passengers in the appropriate way if the client's bag is slightly overweight and check if the flight is full or not. If not, and the bag of the passenger is so minimally overweight allow the customer to board without incident.