Vodacom, get my contact right.

In August 2018 I renewed my contract. The agent told me that it would be an open line but I requested that it be a top up line and it was confirmed to me by both the agent and his manager but it was never made a top up line and was always an open line. On 20 Feb [Ref.1- ********** ********** ] I called to have it changed to a top up. I was told that it could be migrated but the fee was higher than was originally given to me. I told them to go ahead with migration to top up but would still query the rate. The migration to top up was done and the end of February SHOULD have been the last payment for an open line. On around the 6th March an agent called me confirming that my fee should R269.00. On 7th March [Ref. No. 1- ********** ********** ] another agent called and the conversation only revolved around the rate I have to pay and by the end of the conversation he said that Vodacom would have to discount my fee so I would only pay R296. No further details were mentioned about the migration; I did not hear from them again and was expecting to pay a top up fee of no more than R300 at the end of March. I would also like to point at out that at no point on my Vodacom app did it indicate that my contract had reverted back to an open line. There was no sign of an open line bill and I was under the impression that, regardless of my questioning of the fee, that I was still on a top up line. I also managed to buy airtime which I believe cannot be done if on an open line. This is why I was absolutely devastated to find out that at the end of March, VODACOM DEBITED R1400.00 FROM MY BANKING ACCOUNT. When I asked the agent on 06 April [Ref.No 1- ********** ********** ] the agent said that it was changed to an open line on 07 March!!! My question is WHY WAS IT CHANGED?!?!?! I did not authorise an open line. At any point when discussing this contract for that matter! I only realised that this had happened when I tried to buy data on 06 April after my data bundle ran out and could not understand why I wasn’t able to. I also realised, that this unauthorised open line bill had increased between 06 and 13 April even though, I am still within my talk time, still within my sms bundle and the agent on Saturday 13.04.2019 confirmed that I have not used any out of bundle data. So why is the bill increasing? What on earth is going on? I want this contract ONCE AGAIN changed to a top up line, I want my money back and I DO NOT want to pay R479.00 which is the "bill so far" amount on my app. Get this contract right for once and for all!