Stop taking money from my bank account as i never entered into a contract with you!

Netstar has been deducting money from my bank account without my consent, they never called me to even ask if I agree for them to take money from my bank account, I have been complaining about this since august and until today without fail they keep taking debit orders from my bank account, how do you take money from someone's account you have never spoken to? shouldn't you confirm with the account holder before deducting debit orders from their account? and I have been trying to get this fixed as every time I am told to reverse the debit order I get charged by my bank. stop taking money from my bank account because you never entered into a contract with me!