Disappointing service from Vodacom

Pathetic. I upgraded one of my cellphone contracts on 31/07/2023. This was on n top up contract as. I know with an open line you pay a lot of money. So I upgraded over the phone as their service is better than our Vodacom in our town. So without me knowing the consultant that assisted me went and put that upgrade on an open line. I am so disappointed. I really am. I have been a Vodacom customer for many many years. Now I get a bill for R3099.92 I mean really who has that money. I know my account is normally between R500 and R700 per month and that is what I normally transfer every month. I feel that this was not my mistake. Why do they take my acc from a top up line to an open line.