Someone once said that the definition of insanity is to repeat the same behavior again and again under the same conditions, and expect different results...
The same thing happened to me this morning. The same customer called three times within 15 minutes, asking for a product we didn't have. I just wanted to say "No, we don't have it now, we didn't have it five minutes ago- and just to save you time, we won't have it five minutes from now."