Long time customers disadvantaged and offered less that what they already have

I cannot say for how many years I have been a contract customer of Vodacom. I have 3 current contracts on my name and I am due for an upgrade on 2 of my lines. Now I am LIMITED to what I can upgrade to. I currently have an IPhone 8 and firstly Vodacom offered me an USED IPHONE 8 - is this an upgrade or an insult.? I pay R2000 monthly towards my contract and this is how I am treated? My current monthly account on my line *** is R687pm and on the other line I am due for an upgrade for *** R835pm - now they want to offer me less?? I would like any online special IPhone 11 64 or 128GB with 2.4GB data and 200 voice mins for contract *** and the same for contract ***, Currently the online is R679 x 36 months. If I take these 2 phones it will bring my monthly bill down to R1780pm from R2000pm - so why am I being disadvantaged for being a long time customer?