REDCHERUB must be looking for expressions which means "let someone down."
get someone downDo you think that "get someone down" and "let someone down" mean the same thing?
to cause (someone) to become sad or depressed
▪ The weather was really getting her down. ▪ Talking about politics always gets me down.
let someone down
to make (someone) unhappy or displeased by not being as good as expected
▪ The end of the story really let me down. = I felt let down by the end of the story. [=the end of the story was disappointing]