Excuse me, can the American embassy complain about fake marriage?

American Embassy in China?

Or what?

If you want to complain about a fake marriage, you should go to the immigration office where the fake marriage happened.

For example, if AB goes to the United States for a fake marriage and wants A to help B immigrate to the United States, then he should complain about the residence of American immigrants, or he can transfer the complaint through the US Embassy in China or the China Embassy in the United States.