URGENT ATTENTION

I upgrade my cellphone contract with MTN on the 2nd of October 2015.I chose the Sony M4 Aqua. Today 9th November 2015 the phone just stopped working. Everything DEAD. I have had the phone for just over a month. I am so disappointing can scream. Should have listened not to take a SONY. Now the MTN have to send phone in for repair, and the respond is. This happens often with this phone. I mean really???? Often??? Why do you still sell this phone. Now i have to be without a phone for weeks, as MTN will not give me another. The phone is 1 month old, now i have to get a repaired phone. This is unacceptable, and i will not stand for this. As a consumer i have rights.1. I am paying for a product that is faulty. 2.Now i have to be without a device . This is a urgent matter and needs to be cleared ASAP. Unacceptable!!!!!!