Unauthorized debits and poor communication

Sometimes I don't understand MFC how they operate, they just debit money from my account without my consent, someone just called me and being rude to me and said we are going to debit certain amount when I ask she didn't explain properly I said can you go back and find information and then call me because I don't understand what you're saying then she start to say we will debit it , so because I can't stop them whenever I have cent in my account they will always debit my account whatever amount they want without proper explanation this is wrong can someone assist me where can I lodge complain or which ombudsman can I contact because this is abuse. I don't like what MFC is doing to me , THIS IS WRONG AND ABUSE STOP IT.