Daughters iphone 7 plus microphone stopped working. She reckons after the ios upgrade a few weeks ago. Ive tried rebooting, cleaning out the usb etc. The microphone appears blanked out when she tries to make a call or uses the camera etc. The voice memo app wont work becuse the mic is blanked out. The phone works if hooked up to a bluetooth microphone. It appears to be a common 7plus problem. The phone is 3 years old. 

I havent carried out a factory reset yet. I will try tonight. If that doesnt work any recommendations where to take it for repairs.It looks like a motherboard issue ( from googling). I am based in the Auckland CBD.