Being ********** shocking servce

I took out a data contract in March. I spoke to Stanton Greyvenstein in retentions who mentioned the contract I had said Iw ould like to take out was an open contract - I then asked what that was and he proceeeded to explain that there are open and closed contracts. He said it would make sense to take a closed contract as then you can always top up and won't end up with a huge bill. I chose the closed contract. I have now received my bill and have been charged in excess of R1300 on data charges. As it turns out I am told I selected a open contract. I have listened to the voice recording of the conversation and it is interesting to note the that part of the conversation about the closed and open contracts that we had is not audible. I would like this contract to be changed to a closed contract WEF and also would like to make an arrangement to pay this account of R2 000 off. I personally do not feel I should be paying this amount as I did NOT chose an open contract. How stupid do you think I am? I am sure the recording has been tampered with. I have as a result made a direct transfer to Autopage for this contract of R600 this month. I will not have you debiting that amnt.