mic not working for phone calls but does for video

Had this problem for ages and still not resolved it. The Top mic is workin as videos have audio and so does viber and Skype calls but no mic for either calls, voice control or voice memos. I have replaced the lower mic but still not working . Tried the cardboard trick but that didn't work . Switched mb to another case but still same issue ! I'm totally stuck . Have reset the phone too . What does work are headphones and speaker when selected.