Autopage not fair to customers.

I upgraded to a new phone. It worked for a week and then it was just dead I took the phone back to the branch and they send it back to head office for repairs weeks later I collected my phone and it was working except that the phone was a used phone damaged on the casing and durt alround the buttons. I told the lady at the branch that I was not happy about the condition of the phone and she confirmed that they replaced the phone and there was no repairs done. She emailed head office to tell them that I am not sattisfied because I upgraded to a new phone but got back a second hand phone instead. Now they blame the branch for this misfortune and that's the end of it. What can I do this is unfair I pay for a new phone but get a second hand phone? The lady at the branch is in the middle and dont know how to sort this out. All I want is s new phone since that's what I am paying for after all.