IPhone :: Filming Video With It Camera App Has No Sound?

I have a serious problem with my iPhone.When I use the camera app to shoot a video sequence there is (almost) so sound. You just hear white noise and the real sound is almost unhearable quiet. Tried it with the internal mic as well as with an external mic. But! If i use the voice memo tool - the audio recorder - the sound is excellent. Loud, clear and crisp.Why does the camera fail to record the sound whilst the audiorecorder just does it perfectly.I called Apple Support. Despite the fact the guy on the phone did not seem to have understood what I described, he just said, i should reset it to factory settings and if tah wont helf I could send it in for having it checked for as little as 160 Euros.