Medicare & Medicaid maintain a list of practitioners not eligible to submit claims for service. You can find it at
Search the Exclusions Database | Office of Inspector General I ran a search for John Santos, Adam Santos, Santos Urgent Care and 441 Urgent Care LLC and none of them came up.
I've used this clinic for years and been happy with the service. But before I go again I will call them to verify whether they take Medicare and my secondary provider.