I too have a case manager through my insurance company as well as a daughter who works for a very large insurance company and used to be a case manager herself. A case manager's job is to support you, not the insurance company. Obviously, they aren't going to go against your policy, but they will do all they can to make sure you are getting the treatment you need. Mine has been very supportive and even mentioned the possibility of getting additional IVIG during a period when I wasn't doing to well.

Don't be scared, most of them are there to help you. Good luck!