Addedbe debit order

Fnb is authorizing an unknown debit orders been taking money from my account I ve been reversing unknown debit orders as from the beginning of Jan 2015 till today Jan 2016 from different companies small amounts below 99.00 rands and some 150.00 to 200 rands . And yet Fnb isn't doing anything I'm sick and tired now I'm going to close this Fnb account and go to another bank for a good service. I'm sick and tired of this thing it is really working n my nerves