Poor customer service

I am very disappointed with the service given by apple store in centurion. I bought a phone at this store, 7 days later i found the device to be faulty and i went back to return the device. this product was tested to confirm the fault. The device was taken for repairs on the 16 August 2017. On the 18th August 2017 i got an update via sms from apple service center that the device was on a diagnostic status. On the 25 August 2017 i went to the store to make follow up since they were not updating me. they told me to bring the box and accessories that came with the phone which i gave on the 27 August 2017, I was told by one of the technician i will get feedback the following day (28 August 2017). Unfortunately on tuesday the 28 August 2017, i did not get feedback on 31 August 2017 i went back to the store to make follow up again, i was told that according to their system, the box which i personally gave to the technician was not received by the apple store service center. The technician was called in and he confirmed receipt of the box with the receipt. The technicians told me the manager is aware of the situation and i will be updated before end on business day, Unfortunately i was not updated later that day i went to the store and i was given the number for the service center and was told to call them.This morning i got the same message via sms i received on 18th August 2017. i am very disappointed with the service provided by this store, i have been using this brand for a number of years. I want a new phone if that's difficult to do they must give me my money back