Shocking service from Telkom regarding Showmax cancelation!!

Please can someone tell me if they have also had a shocking experience with Telkom while trying to cancel Showmax off their account? I have had confirmation from Showmax that they have not received any money from me since beginning of last year yet Telkom have continued to debit my account. I have had the most awful service trying to sort this out and Telkom will not stop debiting my account. I have subsequently stopped all debit orders from them and now they say that I have to pay the so called outstanding amount before they will cancel Showmax from my account.....and if I don't pay, even though I do not have an active subscription with Showmax, they will basically Blacklist me and hand it over to attorneys for collection. I am at my wits end with this....Please can anyone advise me on their experience or what to do next.