Amazon.com (US) - Terrible Experience & No Accountability

I purchased a Iphone 7 whilst in New York, and I was told it will work in South Africa...it was unlocked. When back in SA, the phone would not switch on at all, even with charging. I logged numerous cases with Amazon to find out the best way possible to deal with phone. They have not been helpful at all, I have now requested a refund and for me to ship the phone back. then they said I must claim form the a-to z guarantee which I did. Today I got a response that the claim was denied with no further reason. I am very disappointed at the service as the phone has not even been used, they took me from pillar to post and took no accountability for their part in resolving this. I want my money back, so this will also go to the Consumer Protection Act Complaints.