Bad service and administration

I have a monthly debit agreement on pricelock, and I've never missed a payment. For September I was debited more than the agreed amount, and when I called to query the account, I was told that I made an arrangement to pay more because I owe them R3000. When I explain to the consultant that I've never missed a payment, he tells me that there's a call recording for the arrangement with them. I asked him to listen to the recording and tell me who they were talking to and what the arrangement was, he tells me that the call was not recorded. When I ask him to fix whatever problem they have with my account, he tells me that I have to pay the amount I owe and he didn't want to listen to what I had to say. I will go to their offices to lodge a formal complaint and also query how did they make agreements in my account without my knowledge. Really bad service and administration from MultiChoice.