Neuropathy

I have a patient with diabetic peripheral neuropathy and foot ulcers. I have been debriding the ulcers every two weeks, and we have billed out CPT 11042. Cigna has denied our latest two claims and the EOB says, “Procedure code is invalid for DOS and global.” There is no global for CPT 11042 and there should not be a procedure code invalid for any DOS with these claims. Any thoughts on what to do next?