Unable to upgrade my phone worst service

worst service ever I have been trying to upgrade my phone but wow firstly I called the call center, and I was advised that I'm on the old system I need to visit the MTN STORE. Today 2023/01/26 I went to 2 different stores I'm being told that I'm on the old system and they are unable to assist me? kanti who's fault is it that you changed your system? maybe it's time to move on