Poorly Trained or Withholding Information

I had to send in my iPhone 7 in because it no longer charged or switched on. I took it to the Clearwater iStore where I was asked to pay R500 and then my phone will be sent to core for repairs. I was then asked by core for the pop, and even after i explained that i got the phone on an MTN upgrade, they refused to repair the phone. Now if the person that booked my phone told me that i need the POP or documentation would have tried to get them from MTN before wasting my time and sending my phone to core. I wonder how many other people spend the time that they have to take off work because the staff at Clearwater iStore is withholding information or just poorly trained.