Place of Service POS and insurance denied claim

Had an FNA done (hospital outpatient), referring ENT (who is part of the hospital system) ordered FNA sample sent to an external affiliated lab for flow cytometry (unbeknownst to me). Insurance wrote off all the flow cytometry technical charges (thank goodness because it totaled close to $11,000 and I was in shock that info wasn’t provided during my initial $1040.00 patient responsibility estimate which I paid beforehand). Insurance denied the external lab’s professional interpretation report charge of $553 (codes 88173, 88189, 88306). I had to call insurance three times (first two times they just said claim requires an "office visit code", third time finally told me the $553 lab claim was denied because it showed place of service as “office” and as such it requires an office visit and if there’s an error just resubmit the claim. Tried calling lab multiple times for help, said their claim review says its correct but ordering ENT provider must give them instructions on codes and code changes to resubmit a corrected claim for coverage. Called ordering ENT provider's office twice for help to double check and they said they don’t understand what an “office visit code” is. At my wits end here because nobody wants to look further into this to determine if there was a true coding error that needs correction and/or if the claim can be covered. Anybody have any feedback, thanks.