DEFECTED HANDSET (MOBILE)

I BOUGHT THE HANDSET (LENOVO A850, BLACK) ON 24th APRIL’2014 FROM AMAZON.COM. I FACED LOTS OF PROBLEM AFTER 3 MONTHS. THE DISPLAY OF THE HANDSET GOES COMPLETE DARK AT THE TIME OF OUTGOING AND INCOMING CALL. I WENT SERVICE CENTER 7-8 TIMES. THEY REPLACED MOTHER BOARD AND SENSER OF THE PHONE. BUT THE PHONE STARTED FACING THE SAME CONDITION AS BEFORE. I REPEATEDLY ASKED LENOVO CUSTOMER CARE TO REPLACED MY HANDSET. BUT THEY DIDNOT TAKE ANY ACTION,

I AM FED UP WITH THIS HANDSET. IT IS NOR REPAIRABLE.

KINDLY SORT OUT MY PROBLEM ASAP.