Worst service

I'm struggling with telkom, I upgraded my contract and I was advised to pay the balance of my old device before the debit date in August. I did and received confirmation that my payment was received on the 31 of August my account was debited for the amount I have already paid then I reversed the amount as I have already paid. In September I noticed my account was not debited I called telkom billing to make them aware that they did not debit from my account then the telkom is blaming it on me and I have to be accountable there a fee of more than R300 added saying it is the reversal fee which they took Doble the money from me. Now the failed to debit and they want me to pay from my side,my worry is that I will still ve in the same situation where I paid and still got debited the consulted could not assist all the best thing she just blamed everything on me. Very disappointed