Bad customer service

I went to Ok to do my groceries on Saturday, 16 September 2017. I was on a a long que and the store manager came to greet the white male behind me. He looked in his trolley and went off to speak to the lady, whom I found out she was a floor supervisor. He said something to her that caused her to request a cashier to open another till, as the line was very long. The floor supervisor came to call the white gentleman behind to proceed to the newly opened till, which he gladly did. I asked the manager why was that and he told me if I had problem, I must stop buying at OK. The manager was very ****** and rude to me.