Upgrade

I am with Vodacom since 4 years and i got a SMS for an upgrade, i was super excited. At the moment i have he iPhone 8 and pay R870 per month - never skipped a payment. Now i went to the shop and got advise that i am indeed qualify for an upgrade, but that my portfolio only allows me to get a phone that is less than R420 per month. How does that make sense? the only explanation i got was that i apparently must have missed a payment, which i didn't. or maybe the fact that i don't have credit. I don't own an account, meaning i don't have credit. i don't want to get credit in any way - since i just only like to spend money i actually have. Which normal people would see as a good thing, but Vodacom apparently wants their clients to have dept. So i asked the consultant "you guys really force your customers to go to other providers hey?" and she was like "sadly yes we do, we really do." even herself realized that this all made no sense. If one pays R870 for 4 yrs how does it make sense for you to go and say, now you only qualify for R420 and if you want the iphone XR you have to pay the difference of R12000 - please in what world does that make any sense to you? worst service and appreciation of customers - ever.