Not getting a proper interview

I am very dissatisfied with the treatment I received yesterday when I went for my VISA interview. I got the lady at the interview section and she asked me 4 questions(why am I going(attend a religious conference&tourism), how long am I going(12 days), Who is paying for it(Myself&my boss is paying for my plane tickets) and what is my salary(R7000)) I answered all of those questions honestly and had documents to back up what I was saying. However the lady did not look at one of my documents after I answered that all she said was "unfortunately your visa is denied, here is a paper go read it" So I said to her "But here is my documents, she said no I already denied your visa". While I was answering my questions, she was busy **** typing on her computer. I feel I did not get a proper interview for the amount of money I had paid for the visa. I am not the only person who went to this lady yesterday and did not get our visa approved. I don't know if she was having a bad day or what but we all got treated unfairly by the hand of your working. Yet everyone who went to the guy who was on duty got their visa approve and we had the exact same reason for going. How can she feel I will not come back to South Africa if she did not look at all my documents I took with to support my claim that I have a strong tie to come back to South Africa.