Had enough of Samsung S5 Mini phone!!!!

I am extremely unhappy with my Samsung S5 Mini as it started giving problems from the first month I upgraded my contract at Vodacom Menlyn. I have been to Vodacom at Menlyn Customer Care 4 times, they gave me a new battery for my phone but the problem still persisted. I took my phone the second time to Vodacom and they send it to Samsung to replace the main board but still I have a problem with my phone and it is not functioning as it is supposed to. The device turns off by itself no matter what my battery life is, and then my alarm doesn't go off, this is totally unacceptable! TIME IS MONEY, for me with my business Vodacom and Samsung is costing me money every day, losing money as clients can't get hold of me, I don't have time to waste, to go again and again to Vodacom to send my new Samsung S5mini for repairs! It's a new phone and not supposed to give me so much trouble. I have had enough with this phone and my time that is being wasted to go to Vodacom's Customer Care every single time to sort this out my business is taking a big knock due to this. It is now the 4th time at Vodacom and I have had ENOUGH of this SAMSUNG S5 MINI Samsung South Africa should give me a new phone!!