Dey & Co. — Didn't get my phone back

Address:

Kolkata, West Bengal

I debjani das from sodepur, kol - 700113, i gave my mobile to the shop name dey & co. (46, r. N. Avenue, sodepur, kol - 700110) from where i had bought the phone because my mobile was creating some proble in switching on & it was under warranty period. . They sent me to the videocon service center name 0 mobile (15 icroad, rahara nandankanan, kharda, kolkata westbengal) . . . Initially they had said to give my phone back within 10 to 15 days. . . But they kept my phone for approx 6 months & finally they gave my phone without solving the problem. . . Due to their fault my warranty period also got over. . . After that i again gave my phone to that shop. . . But still now i haven't get my phone back. . . Kindly if you help me to solve my problem i will be greatfull. . .
My phone details is videocon a15+ white. . .