Infuriated!!!!!!!!!!

I received a call about an offer on my current contract. I was told that I'd receive 5GB data per month at R85 less than my current account. My daughter helped me in trying to understand the caller better as cellphone terminology isn't my strong suit and we made it clear to the caller we couldn't afford a higher bill and repeatedly asked the caller from vodacom to ensure that my account would not increase but remain the same and she repeatedly assured me of this, to which I then agreed based on my understanding. I had no idea that what she actually meant to promote was a data bundle at R85 less than the current rate per month in addition to my current bill. So color me surprised when I discover my bill for the end of this month will be doubled!!! I'm sorry please educate your sales people on proper communication!!!! If someone asks will my bill go up, get you dam math right!!! I want no part of this type of service.. This better be alterised or I will take my business elsewhere!!!!!!