Overcharging

I took out a new contract with Telkom Mobile that was on special for R599 for uncapped LTE. I spoke to Nokwanda and she reassured me that my existing LTE contract will stop once the new one starts. I have received the new one and have been using it already and today I get an invoice from Telkom with the old LTE and the new LTE being charged for the month of October.. The old LTE was supposed to fall away and the new contract only was supposed to be billed.. Furthermore the invoice for the Unlimited LTE that was one special and confirmed with Nokwanda to be R599 a month is being billed at R823.77. What is going on here! You are charging me for one service that isn't being used and you are overcharging me for the service that I am using! Plus you already deducted R599 from my account for the unlimited service at the end of September so surely that payment should be for October anyway! Telkom your urgent attention to this matter would be appreciated!