Bad Service , incompetence and riproff from CNA

I bought a brand new phone huawei y5 on the 26/10/2018 by maponya mall on the 15th of Nov 2018 the screen stopped working, took the phone in apparently it cant be exchanged for a new one but have to send it for repairs, its been three weeks and no one at the store don't know the progress of the phone, this is complete incompetence, i want m a brand new phone or my money back, i bought the phone cash and expect to be assisted, how can i buy a phone and not even three weeks the phone stops working. i cant accept such service its ridiculous. I need someone to get back to me as soon as possible has ill be taking this matter forward . for heaven sake this is the festive season and u guys expect me to stay without a phone.