Incorrect Charges on Statement

So I went and upgraded my contract in December 2019 as I wanted a cheaper contract. The person helping me stated that my contract would only be activated in January 2020 as I came to them on the first. When I got home I noticed my contract was already migrated to the new contract, so I thought they activated it already, fantastic right? Not so much, in December I get a statement and it says I need to pay for my old contract for December, which is about 4 times the price of my new one, so I thought maybe in January there will be some form of compensation, so I left it. Get my statement in January and now they have charged me double, the new contract for January and the New contract for December! So I phone Vodacom and ask that they have a representative phone me back, couple days pass, no phone call but the problem has been resolved according to Vodacoms app. I phone them and they say they have decided to credit my account with R200 which doesn't even cover the new contracts cost! I say they need to contact me because I am not happy as in December I paid for an expensive contract and only had use of the cheap contract. A few days pass again and I get an SMS again, not a phone call, an sms stating that they are right in giving me that credit and not the other contract amount. I have been a Vodacom customer since I was in school and every time I have a dispute it seems that Vodacom care less and less about their clients.