First thing you will need to do is stop the ACH on your account, You can do this by sending them a letter with your account number and tell them you
revoke the ach on your checking account, include your checking account number in the letter. At the same time you should send them a revocation of voluntary wage assignment, just in case they slipped this in there on you. That way they can not touch you pay check.
What state are you from? You will need to know this to determine if you are entitled to a refund. Please let us know what state you are from?