Ackermans has false policy that they can't explain themselves, they don't follow the NCA

This store showed it's ***********, doesn't have standard procedures and they sell us lies. I bought a cellphone on a Monday the 26th of March the cellphone on display showed me good quality same features as that of a Samsung grand prime and the phones were both the same price, in my decision I took the phone home only to find out the features were not up to my liking the 8MP Cam was not nice. I called Mtn to ask about this (as per phone was of Mtn) they told me that's how the phone should be there's nothing wrong with it if I don't like it I should exchange it at the store I bought the phone from. On the 29th I went to the store as the Ackermans store policy advise that cellular phones are to be exchanged within 7days of purchase provided they have no signs of damage or has been repaired elsewhere. The manager of the store refused to exchange the phone for me,she said they have to rather take it back to the vendor for 3 weeks for repairs, I told them there is nothing wrong with the phone. But they refused to assist me. Working for a retail company myself I know my consumer rights and of the NCA, I called their head office to assist me but still I never got help not even a complaint number, they gave me a name of a person as follow up reference. I am so disappointed in this store as I have bought 3 cellphones with this store before and have never encounter this problem. They don't abide by their policies and allow displays that don't show customers full information about the product they cell. I am now sitting with a cellphone that uses up all my data due to its slow processor, it's battery is weak and this may cause me more problems along the way with the warranty expired, hence I wanted to exchange it for another one. I am really angry this is my last time in this store.