Faulty Samsung S6

I upgraded my cell phone to a Samsung S6 with Vodacom 4U at Greenstone, one week later the phone will not switch on. I return it & I'm told by the store it's an OBF \Out of Box Failure". They sent it to Vodacare & they have now rejected the OBF. Now the phone is being sent to Samsung. Why should I have to be inconvenienced by a faulty product made by Samsung & sold by Vodacom 4U & sit without a phone for 2 weeks & counting."""