No service/ Incorrect billing

In the month of July / August Telkom activated a Service on my line that I did not ask for. A R200 talk time was added to my spending limit without my consent. My girlfriend was surprised that her airtime never got finished but I found out from Telkom that a service was activated on my account. I asked for this service to be cancelled but it never happened. I received my Invoice and saw for the month of September I owe R2457. I refused to pay that money but Telkom debited the money from my account now in December.