“Thank your customer for complaining and mean it. Most will never bother to complain. They'll just walk away.”
“A thankful person is thankful under all circumstances. A complaining soul complains even in paradise.”
“Folks with most to complain about seldom complain most.”
“The silly when received exclaim loudly; the fool complains; the honest man walks away and is silent.”
“That's typically what writers do; we just sit around complaining most of the time. And the better things are going, the more they complain.”
“You’ll never change the world just by complaining.”