Z00.110 denial

Recently had two claims for above code denied as already paid. One of the local hospital nursery (MD and NPs) have routinely billed NB admission as well as next day note (if 3 day stay) and Z00.110 code on discharge day. I’ve spoken to the Neonatal MD and she claims that the hospital has told them to bill this code. Perhaps they’ve received denials before, but mine have just started… Is there a ruling that prohibits them from doing this on the basis of “place of service” ??
Suggestions re how to handle w/ insurance companies?
Thanks in advance for your ideas/help…