start with your insurance company. if they're sending your insurance one set of codes and then a bill to you for different ones, that's proof of fraud right there. your insurance company is going to take swift action to make sure they're not paying more out to the doctor than they're supposed to. compare the explanation of benefits you get to the bill you get, and if things are different, that's your proof.

otherwise, contact dobi which is the arm of state government that deals with this sort of thing.