Sony India — UNWANTED NOISE IN DURING CALLS

I WAS PURCHASED SONY X PERIA M LAST YEAR AUGUST 2014. AFTER 4 MONTHS MOBILE HAVE PROBLEM IN DURING THE CALLS SO I GAVE THE MOBILE IN SERVICE CENTER @ K.G ELECTRONIC TIRUPPUR. TEMPORALLY PROBLEM RESOLVED. BUT AGAIN THIS PROBLEM CAME FOR THIS MONTH AGAIN I GAVE SAME SERVICE CENTER. I DON'T KNOW WHY THIS PROBLEM WILL COME FREQUENTLY KINDLY GIVE ME THE PERMANENT SOLUTION NOW ALSO CAME SOME NOISE AGAIN SERVICE CENTER PEOPLE TOLD 2G/3G NETWORK PROBLEM SO THIS ERROR CAME.I AM TOTALLY UNHAPPY WITH SONY MOBILE. LAST 10 YEARS AM USING SONY MOBILE ONLY.CONTACT-[protected]