Damaged goods and unhelpful staff

I bought a phone on the 12th of November and it gave me a problem the first week, I took it back to the store where I bought it and they reset the phone and said it was fine it wont give me problems anymore, even when I told them that it sometimes refuses to charge. I then took it back on the 3rd of December because it wouldn't charge again and it wont come on the consultant told me that it's not their problem and all she can do is take the phone and return it to the cellphone company and I can only get the phone after 8 weeks. They are not responsible for the phone or how long it takes for it to be repaired. In the interim I must just buy a small phone which I can use because they don't give replacement phone even though I told them the first week when I got the phone to replace it as in their policy they say u can return it within 7 days and they refused saying the phone is fine. Now I called the MTN head office and they told me that they haven't received the phone it shows on their system the phone was only collected by the courier service this Wednesday and they waiting for it. What the hell does Ackermans being a brand expect me to wait for 8 weeks without a phone. This is a new phone it's not even a month old and already it's in for a repair. They call themselves a good brand. They are the most useless store I have even bought stuff from and as for their rude stuff members they need customer service training as they know nothing about customer service. As a customer care agent you never tell your client that it's not your problem they must figure out a way to sort them selves out. I just wish people would know what a useless service ackermans gives to their customers.