Pathetic service from the manager of Community Motors in Albert Road, Salt River

I visited Shell Community Motors branch in Salt river this morning on my way to the office. I am a regular customer and the majority of the staff know me. Today, I was served by a very rude manager. I asked him to assist me to redeem my V+ card point because I wasn't sure of the procedure to be followed. First, I noticed he was rushing me and I kindly asked him to slow down because he was confusing me as he was lacking patience and what I couldn't understand there were no customers behind me. He rang my goods and ask how much am I going to spend, I told him the total amount of the goods. I then told him that I wasn't aware how much was in the card. He said in the most rude/arrogant manner, shouting and embarrassing me in front of his staff "But you said you wanted to redeem points" I told him, that I had indicated from the beginning that I do not understand the procedure and therefore I would have expected him to lead me with questions such as "Do you know how much money is in your card?" That is proper customer service! He continued shouting at me as if I am his child. I asked him who was he trying to impress because surely he was doing this to show people that he is the manager and therefore he has the final say. I've never felt so embarrassed in my life. Even the staff that knows me, were very surprised asking what happened because they know me very well. I phoned customer service department at shell, they promised to come back to me ... I am still waiting. No one called. I am dissapointed at Shell being such a big company to hire such a manager who lacks customer service skills. He is very rude and lack manners. How can Shell put such an arrogant person in front of house? Shell you have lost me as a customer and I will make sure that I spread the word! I will definitely walk in at your regional office in Cape Town to escalate this matter.