Customer service

What I-store centurion and MTN store centurion did to me was very cruel, disappointing and hurtful. Considering that I have been their loyal customer for so many years. I got an whatsapp text from MTN saying I qualify for upgrade, I went to centurion mtn store and I was told they don’t have the iPhone 13 128g and that I should go check it at istore centurion. I then went there when I got there we got stuck on otp because the number that I used for when I was creating my contract I changed it. I asked the istore sale person to change the number and update it, they said I must go to mtn store and ask them to update it. I went to mtn store when I got there they did wanna help me and said istore people only wanna deal with sales and they don’t wanna help their customers but I begged them to help me they ended up helping me, i told them that there’s an amount I need to pay before I could get the upgrade and asked if I should pay it at mtn store or at istore and they said I should pay it at istore since that’s where I’m going to get the phone. Okay I went to istore when I got there they tell me they don’t do billing I should go mtn store. I was just doing up and down for hours and I even took half day from work but I just ended up not getting the help. I’m very disappointed and hurt