Unauthorized debit orders

It happened on the 25th and now again today another unauthorized and unknown debit order went through from my account. Last time I reported this amd the consultant that was assigned to help me expected me to call that particular company. How can a company that I dont know have access to my bank accoint details is my major concern. I'm consider switching my salary and debit orders to another bank then closing the account. Bank charges are involved and no-one cares if you know about the debit or not.