please help me

i am a mechanic and at work we have a truck that comes by to sell us tools
(snap on)i purchased a 600.00 tool and set up a biweekly payment of 50.00
this week i payed him 50.00 cash on Monday on time like i do every payday to
later find out he had taken 50.00 out of my bank account on Sunday. he
overdrew my bank account and this is not the first time he has done this
with the employees here . again he was NOT authorized to take money out of
my account . he only had the bank account number in case i did not pay my
bill or quit work and he couldn\'t find me to pay my bill .