Medicare doesn't pay for physicals using the 99396 code. They cover annual wellness visits, using the appropriate G code. You may want to correct and resubmit the claim, if what the provider did meets the definition of an AWV. The patient does owe the billed amount from the 99396 since that service is statutorily excluded, but I would think twice about charging them for it, if they didn't know it wouldn't be covered, and especially if the issue is that the claim wasn't coded properly by your office.