Problems with people hearing me iPhone

Yes I have the same problem and would be keen to now how to fix the problem.

I am having that problem now.  I've made 2 trips to the Genius bar in the past week and they cannot diagnose what's wrong.  They've done tests and said it's not a hardware or software issue.  I restored the phone and it worked for a day.  It doesn't work on bluetoooth, iPhone or speakerphone mode.  People just cannot hear me!  I'm so frustrated at this point with their inability to fix it.  To top it all off, they are saying they cannot replace it under our purchased extended warrantly because there is a totally unrelated crack in my screen.