Epimone (e-pi’-mo-nee): Persistent repetition of the same plea in much the same words.
X: I want a car. Can I please have a car? I’m begging you for a car. I need a car. All my friends have cars. Please, just one little car. I’ll even take a used car. Can’t I have a car?
Y: Some day you will have a car, but not now. You don’t even have a driver’s license yet! After you get a license, we’ll start talking about a car. In the meantime, please, no more asking.
Definition courtesy of “Silva Rhetoricae” (rhetoric.byu.edu)