MTN doesn't assist on my upgrade if its a contract which is cruel

I wanted to upgrade my MTN contract by getting a new iPhone 13 mini in late Jan 2022. I was told by Pfani Nemadevhele that MTN doesn't have stock & I may get it in April which is very far for me. Surprisingly, my wife was told the same story in Jan 2022 when she wanted a iPhone 13 pro max. But when she paid it cash, immediately the was stock was there & it was delivered within a week. Meaning they prioritize cash than contracts which is very cruel. I am angry & very disappointed that when we want a contract, MTN comes with excuses etc. I really need the phone as of yesterday as my current phone has battery problems. I would like to know when will I get my new iPhone in Feb 2022 as its long overdue now as we in the 3rd week now.