I had a friend who became an aide to a famous, elderly congressman. (There is a funny coincidence to the topic here in that he had previously been a senator, and per protocol the correct thing to call him was "Senator" even though he was then a representative.) Anyway, the aide's name is a Hebrew name with a close English equivalent -- think Avraham for Abraham. He never, ever went by Abraham or Abe. The Senator just couldn't get it right, despite what I am sure were only good intentions -- he just kept calling him Abraham or Abe. Finally, one day when there was an appropriate moment, Avraham said to him, "Senator, the people closest to me in my life call me Avraham instead of Abraham. I would be so honored if you would do that, too." The Senator was charmed, and he never got it wrong again!
(A great example of getting the job done by asking for a favor, help, or a courtesy instead of pointing out why you are right and the other person is wrong.)