Customer service complaint

I would like to express my disappointment with the service I recieved at Woolworths Festival mall today at the cellular phone counter, my sister bought a new cell phone yesterday at the same store and was assisted by the branch manager Pat Mokoana, she explained to him that required a cellphone that can take 2 sim cards, she intended to purchase a Nokia C1, but was told by Pat Mokoana that she will need to use the phone with an MTN simcard but she declined and said she will only be using a vodacom and Cell C sim card, he (Pat Mokoana) recommended the Nokia C2 from the vodacom range but he failed to explain that it was only taking 1 simcard, the phone was purchased and my sister only saw that it took 1 simcard when she got home, I took the cell phone back to the store, where the sales lady at the counter told me that she processed the sale yesterday and made me aware that they don't take cell phones back or exchange them or refund if there was a mistake, but I explained to her that it was the person who was helping my sister who made the error she called the branch manager who was indeed the person who assisted my sister, he rudely told me that he explained to my sister that the phone only took 1 simcard, I told him that it is not true because if he did my sister would not have purchased the phone especially because it was more expensive than the Nokia C2 that she initially wanted, Pat Mokoana rudely dismissed me and said if I don't believe him than it's case closed, he rudely walked away, the sales lady apologized for the misunderstanding