Unauthorized debit order

Telkom is basically going against the mandate or agreement we entered, anytime they think they can debit my account they do so, they are inconveniencing me , I can't close my bank account because of them, I am not behind on my account but they keep on debiting my account, do they even know that bank charges us whenever they do their ****gish behavior of debiting my account without my account when I don't have enough cash?. I want my R238 back in my account please, I wish no one take contract with them anymore,I had people complaining about this company and never believed, now am seeing it myself.