MTN opens up accounts without proper verification.

So, I woke up this morning to an unauthorized debit order on my account from MTN. This is a company that does not request permission to do a debit order on your account. According to my bank, there are a few companies like that, so the debit order mandate is not full proof. I stopped this debit order. I mailed MTN ***** and then they tell me to call customer service 135. Let me tell you that when you call this number, you don't get through to anyone. So, MTN, how do I remove this account from my name? What are the steps? Who authorized the debit order, where is the copy of the ID? I want this remove from the credit bureau immediately. And next time, ask for a mandate to be approved.