Hi , i have the same problem . It seems to be a known problem with the experia m2 . You can try a few things yourself.
1 Remove simcard and stick on the white side 10 strips of tape, this ensures that the simcard at the contact point is pressed .
2- you can buy a new simcard PCB and fix yourself. Make sure you buy for the right type for example D2303, D2305.....
https://youtu.be/wADy76yTen0
Success,
Danny