She needs to be stopped, in a prompt, yet civil way. This should be handled by management, if it continues, report her to the management. This happened to me in a similar situation only it was with a nurse practitioner that the office staff was calling her Dr. “Smith”. I informed the staff that was breaking the law by going by Dr. and I would be reporting her, the office gal said, oh we just call her that because she likes it! I said practicing medicine without a license is against the law. I asked to talk to the office manager, told her about what was going on and she told me it would be taken care of. It stopped immediately!