Manager told me to take the matter up and she won't assist me. - Consumer Complaint for PEP STORES

I bought a phone to work with bolt driver app in Pep cell store in East London Buffalo complex. I downloaded the app and it gave me an error message that says "display over other apps, feature not available, this feature has been turned off because it slows down your phone" I spoke to the person who was selling me the phone and she even tried herself to fix the issues and didn't come right also and she told the manager who was at the back office and told me to wait for her. I waited for +45 minutes for the lady and i ask the cashier more than 3 times to please call the manager. When she came she told me i must take the matter up she won't assist me and she even did not take the phone and see if the app is really not working. She only ask me did i told the cashier when i buy the phone if i am going to use if for the Bolt Driver app and i ask her if when i buy the phone do i have to state a reason for me to buy the phone and she reply yes i have to. So the phone doesn't serve the purpose, and i wanted to exchange and take the other phone. All I needed was to return the phone and buy a better for in the same store. The manager doesn't have customer service at all and she approach me with bad attitude. Please help me