Staff at OR Tambo need to go for customer service training and professionalism training

I booked a flight to go to DBN from JHB OR Tambo yesterday the 28-08-2022. Because I got to the boarding gate a bit late; due to the boarding gate times being mixed up; the staff there were extremely rude to me and shouted at me for not being on time. They refused to let me on the plane even though the plane did not depart as yet. There were no announcements made for me over the airport intercom and no interest shown whatsoever from all the staff at the OR Tambo airport that work for this airline. If they don't want to work for a living then they really must quit their jobs and give it to more deserving people because there are a lot of people in S.A that need employment. There is no customer service skills or any skills whatsoever. Extremely horrified at the experience I went through. You would think I was going to board the plane for free and didn't pay for my flight.