OUT OF BOX FAILURE DECLINED

I upgraded my phone at the Vodacom Shop N1 City. The phone I upgrade to was a Samsung A3 (Gold). <br> The same day I started using the phone, the phone would constantly restart for no apparent reason. I contacted the store the same day and they said it must be sent away for assessing. I took the phone back the next Sunday only to find out I have to wait 7-10 days for the assessment. I called a week later only to find out the OBF is rejected and the phone has been sent to ARC for repairs. Why am I been penalized for a defected phone which I am paying for. Why has this not been replaced almost instantly as the fault was reported the same day I got the phone. This is supposed to be a new phone which is now repaired. I shouldn't be held liable to pay for the first month of this contract as I have not had the use of the handset also I am inconvenienced by being without a cellphone.