No flexibility on home internet data plans

I have Vodacom’s 100gb Home Internet price plan. At the time when I ordered it I did not know how much data we would need. I asked the consultant if I could change the 100gb to 200gb if we needed more data, as I wasn’t sure how much I would need. He assured me it was possible, but failed to mention that it would be more expensive than if I had gotten the 200gb from the start. It seems it’s not possible to increase your monthly data plan. My options are: top up your data with ridiculously priced data or migrate your contract but then you’ll be paying way more than the current price of R749 for the 200gb Home Internet plan. In fact I’d be paying nearly R1000 which is even more ridiculous. Why is there no flexibility on your data requirements?