Unnecessary upgrade because the no longer offer the SMART TOP UP XS+ that I have a contract for.

I was informed by a call centre agent that my contract SMART TOP UP XS+ is no longer being offered by Vodacom, and that I am being "upgraded" to a bigger package because of this. The cost will go up aswell. I DID NOT AGREE TO THIS, AND VODACOM CANNOT JUST UPGRADE ME AND CHARGE ME MORE PER MONTH BECAUSE THEY DON`T OFFER THE PACKAGE ANYMORE. We have an agreement for a 24 month period. Kindly honour it. If I wanted a "bigger" package, then I would`ve app**** for a "bigger" package.