Am I obligated to pay a doctor's bill when I have insurance?

I just received a bill that my health insurance rejected because they only allow one consultation per condition per calendar year. When I broke my leg, it required two operations which also required two pre-op clearance exams. My insurance rejected the second claim citing the above criterion. My best friend says I should not pay this bill and suggested that I ask the doctor that did the pre-op exam to re-code and re-submit it. However, when I asked the physician to do this, she said she is no longer affiliated with the health care facility that sent me the bill so she can do nothing about it. This service was rendered almost two years ago and they are just getting around to sending me an invoice. What can I do?