Kenilworth Centre, CPT, assistant manager unprofessional

Kenilworth Centre, Cape Town. I bought a bag of diapers from the Baby Things range and they were too small. I went back a few hours later to get a refund and the cashier says that she can refund it but her manager said that she must tell me in the future not to open the bag they way I did and instead open it another way because it is not fair on the other customers who will want it. I told it has nothing to do wig being fair, how can you sell a bag of diapers that has been opened, its unhygienic. She continues to repeat what her manager says and then I asked to speak to the manager. The assistant manager, Riaan, arrives and I said to him that I donot appreciate being told how I should open the bag and then he goes on a rant if how it is not fair to the other customers. I dont understand how it is being unfair to the customers, are we reselling open diapers? I told him that he has no right to tell me how to open a bag, it clearly says on the packaging that if I am not satisfied with my product then I can return it. Again the assistant manager goes on a rant of how he has to write off every customers returns. As he was talking to me he kept taking a step closer to me, i found him to be aggressive and defensive which is unacceptable. He later told me what more do you want me to say. What happened to apologizing for any inconvenience caused , why are we telling consumers how they should be opening the packaging to their purchases? In the end I told him that I would be taking this further and he cheerfully told me to do so and walked off. Never in my life have I come across such unprofessionalism and arrogant person. Riaan is not fit to be in any managerial position, he has no customer service s****s , no manners, needs to attend a finishing school!