Sony sells faulty phones (Sony M4 Aqua)

I have had this phone for 2 and half months and it has gone for repairs in the first month of having it, last week friday this phone just switched off after a normal day without any faults. honestly I love this phone however I cannot keep paying for a phone that has a factory fault. Sony needs to send me a new phone and a guarantee that this wont happen again. or I will have to cancel my contract with cell c.