Asus India — Signal problem in new phone got repaired 2 times by service centre.

Address: Solan, Himachal Pradesh, 173205

I bought phone in sept 16 found signal problem. Give it for repair to authorised service centre. But proble is not resolved. So i again give it for repair to authorised service centre. I still have problem with this phone. It frequently looses signal and every time i have to disable and then enable Sim. My SIM is working fine in my old micromax phone but not in Asus ZEN MAX. What should i do. I want to get my phone replaced. Can i file legal case against Asus.