Week old phone don't exchange

I waited 2 and half months to get my M5. I finaly did get it and 7 days later. Monday tot Monday( one week) and it started giving problems with battery. I went in on Monday and they told me it is the 8th so the phone need to be send in. This is unacceptable for a phone I had for a week! The service in that store is not at all up to standard. If you have a complaint or query they just put their hands in the air and say we can't help you. I was without phone on contract for 2 months and once again without phone and no service to help the client. I have alot more complaints but can only log in one. So do not buy a phone at MTN they will always find a way out of helping the client and never provide top class service.