Account debited without consent

I have a problem with Clientele they debited my money in my account with out my consent and when i tried to call them to ask about the unauthorized debit they just ignore me, and drop my calls without assisting me. I am not sure how they got my details and they have not provided with evidence that I took policy with them. I am not sure who turn to so I can get my money back and also for them to stop debiting my account without my consent. Someone please help