Unauthorized debit orders going off on random days of the month.

I have been a customer for over 4 years. My debit order date for the last 4 years has always been the last day of the month. For the last three months Telkom has run debit orders in the middle of the month AND on the last day of the month and then billed me a penalty for the failed debit order they run in the month. They have run these extra debit orders without my permission and my knowledge. I only realized this was happening when I read my statement and queried the extra charges. When I call in they tell me the unauthorized debit orders have been ordered by the collections department who apparently don’t need your permission to run a debit order on your account on the 20th of the month. They tell me I need to speak to the collections department but when you call that department no one answers. I tried to call 19 times and every time it goes to a mail box that is to full to take more messages. Correct me if I’m wrong but isn’t it ******* to order a debit order without the account holders permission or knowledge unless the court has ordered the action? I’m so sick of struggling and NO ONE can or will help me. Clearly they don’t need customers so why should they help fix a problem that they caused in the first place?!