Sony India — Xperia z2 mobile, mic not working and been to service center twice

Address:	New Delhi, Delhi, 110051
Website:	www.sony.co.in

I have bought xperia z2 in last may and recently after a system update my mic started working weirdly, other person could not hear my voice and then it became distorted too. I went to the service center they kept it for a week and after returning the calls were received on speaker and with the same mic problem. Now i went second time and after coming back the mic problem still prevails and also my internet is not working on 3g. I have confirmed with the network company its the mobile fault. Can you please give a solution to the same as it is still in warranty.