Anthem not covering bill

Not sure if this belongs here but hoping to get some answers. Earlier this year, during my visit to my gastro doctor, we discussed getting colonoscopy done given my family history of colon cancer. Doctor agreed that he can quote it as “preventative screening” procedure as opposed to diagnostic one. Before I made the appointment, I confirmed with my insurance that it will be covered as preventative screening procedure. During the procedure, my doctor found a polyp and removed it. However, after the procedure was done, I started getting bills from my doctor, radiologist, anesthesiologist, and the facility where procedure was done saying insurance didn’t cover it. Turns out my doctor had entered wrong codes that said it was “diagnostic” procedure. He did resubmit the claim with correct code of “preventive screening” and my insurance confirmed the claim was processed successfully. After the resubmission, all the bills were except facility were fully covered but I am still getting the bills from the facility for about $2K. My insurance says claim was processed correctly. I checked my policy (through my husbands employer) and it says clearly that I don’t have to pay anything for preventive screening procedures. I don’t know what to do next as I legit think I shouldn’t owe this bill but I am afraid they might send it to collections that will only hurt my credit score. Any recommendations?

PS. My insurance provider is Anthem Blue Cross Blue Shield of Texas

Thanks!!