Debit order dispute

I recently upgraded to fibre from Telkom. I was on an ADSL contract for numerous years. Since being on fibre my account was debited more that the contract agreed amount. When I spoke to the call center agent I was informed that I was still being debited for the ADSL line and that I needed to log a call which was done, a few days later I received an sms saying that the call has been closed. On the 15th of December another amount of more than R2000 was debited from my account.