So last week I dropped my iPhone 4, not S (Actually it was accidentally threw) and the back glass breaks and the metal frame or something was bent. I get it to a Mobile Repair shop (My Apple Care insurance plan expired long time ago) and they changed the back and the frame and everything still works but, when I make a call or receive one. The person on the other side of the call, doesn't hear my voice like every time. I checked on Voice Memo and the microphone still works, so i think its just the Frame interference problem on the first version of iPhone 4. So I tried using a case and a bumper but still silence. I took it back to the repair shop and they diagnose the phone and they say, it'll take a few days for them to fully diagnose the problem. MAYBE the Mainboard is damage because of the impact (They say). I wanna know, What are other possibilities? other than damaged Mainboard, and is it a big deal and is it expensive to repair cuz my parents won't pay for the main board 
. Who ever been like this before ? and what happened? (Just wanna know the possibilities and how much. Its destroying my day) Thanks in advance
. Who ever been like this before ? and what happened? (Just wanna know the possibilities and how much. Its destroying my day) Thanks in advance 