THEFT OR UNAPPROVED DEBIT ORDER

A company by the name of Mobilitycb made a debit order in February from my account. i dont know who they are and how did they got hold of my account numbers. This is ***** and theft. This company stole from me without my knowledge and i dont even know what they deal with. Worst part they make debit orders less than R100 thinking you wont notice. this is frustrating as our banks are not assisting instead they will tell you to reverse and then you still pay for charges. How do these people get hold of our account numbers? Im getting sick of these banks