Good grief! / How outrageous! / Unbelievable!
Expresses shock, outrage, or disbelief at something excessive or unreasonable. Can be used for genuinely outrageous things or to exaggerate for effect.
—They charged him three hundred euros for a dinner. —Good grief!
What an outrageous queue, we've been waiting an hour!
—She works twelve hours a day. —Unbelievable!