I am fed up with the service I got at vodacom stor

I bought a new fone Samsung S6 at vodacom store that is in Pretoria central Du Toit Street 3months ago within 2week the fone just died I took it back then the guy said to me that I must take it next door for repair, I asked him why do I have to take a new fone for repair?he told me stories I took it.I got it back in a week the following week it died again I took it back and the guy said to me again to take it back and he said if it happens again we will give you a new fone then I took it in,it came back then recently it restored itself then got stuck there I took it to him this guy said to me it is still under warranty take it for repair then I said no Bro I don't want this fone anymore you told me if I bring this fone 3times you will give me another fone and now u telling me it's 3 different problems if it was the same problem over and over you will give me a fone,I took it for repair told them I don't want the fone anymore they said cool they will send it to Samsung I have to wait 3weeks,within a week they call me and say your fone is ready I went got the same fone again I told them I don't want it they gave me numbers to call now it's dead again.I need help please