Incorrect billing

Last month I took up their uncapped WiFi special at R807 per month. In January the amount was prorated so I paid half. This months’s bill came back at R1500, call center says my contract is not clear what product I took up. I asked the billing department to sort it out and call me back till today nothing has happened. I will reverse the R1500 debit order and pay what I took up then cancel the contract because clearly Telkom is notorious for billing it’s custo incorrectly and getting away with it.