cannot cancel my telkom account

In May this year, I went to the Greenstone branch of Telkom to cancel my Telkom account. They assured me that it would be cancelled on 15 April. To date, and 6 visits later, my Telkom account is still not cancelled. I see that once again, this morning, they have deducted from my account. If I cancel the debit order they will black list me. I will have to go in again today and stand in the queue and waste my time trying to cancel this thing. I have sent emails, which have been ignored, when you phone, you wait for up to 40 minutes for someone to answer the phone.