Taking money out of my account !

I'm so sick of these people. This has now been the second time they have taken money out of my account without me even signing up for anything. I don't even know what the company does, I'm a student !!! The first time the money was taken I called them telling them that there is a mistake and the guy over the phone told me that it wasn't meant for me. It was meant for someone else's account. OKAY ??? So why don't you double check ?????? This is ***** !!!!!!!!!