Schocking service from MTN store

I had the worst experience from MTN store in Canal Walk. I bought a mobile wi-fi router from them last week Wednesday 30 June. The unit worked after the first charge but the battery run down very quickly. When I tried to charge again nothing worked. I even tried to charge it over night. it was dead. Today I went back to the store to get replacement 7 days after purchase. The Sales assistant told me that he could have replaced it immediately if I returned it within the 7 days. in my case the item need to be taken in for revue and it might take up to 2 weeks. I told him that I am not happy and cannot be without internet so long because it will influence my Bussiness. He then told me that if `I do not have the original packaging they will reject it. What BULL. I thought the packaging away because I trusted the items and it worked on the first day. Even when he tested it, he could see it is not working. I informed him that consumer protection act protects me because of the short period after purchase, but that is when he got rude to me. `I walked out and phoned MTN's call centre to lay complaint but that was even worse experience. I was basically told they cannot help me. This is the treatment for Bussiness owner with 4 contracts with them for the last 10+ years. MTN your a disgrace...