talk to a brick wall
be like talking to a brick wall
To be completely ignored or disregarded by someone; to be as useless or ineffectual as talking to an inanimate object. Talking to you when the TV is on is like talking to a brick wall. Hello, can you hear me? Trying to give my grandfather advice is like talking to a brick wall—he's just so set in his ways!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
talk to a brick ˈwall(informal) used when somebody refuses to listen to your advice, ideas, explanations, etc: Talking to him is like talking to a brick wall. He just won’t listen.
Farlex Partner Idioms Dictionary © Farlex 2017