Home Internet data Line Upgrade

I have been complaining about my home internet data line ***) since January 2024 with no resolution to date. I upgraded my line on the 5th of December 2023 to a new package that had a Black Friday special discount with no hustles. On the 31st of December 2023 when I enquired about the data I had on my previous package, the call center agent explained to me that I had forfeited the data due to the online upgrade I made on the 5th of December 2023 and I understood the agent clearly. To my astonishment, in January 2024 Vodacom decided to move me back to the previous 400G package without any consultation and my approval of such movement. I have since been struggling to get a resolution on this matter and the service provider (Vodacom) has been over debiting my bank account without my approval. I called Vodacom several times pleading to them to revert me to the package I had upgraded to in December 2024 with luck. How can I be assisted on the matter? I have been loyal with this service provider for over 10 years now and I’m starting to question the decision I made back then.