REDCHERUB must be looking for expressions which means "let someone down."
get someone down
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]
Do you think that "get someone down" and "let someone down" mean the same thing?