Micromax Informatics — Regarding phone functioning ,and finger sensor

I beg to say that I have purchased micromax in b 32 gb 4 months ago .phone is not working efficiently. Firstly the finger sensor get stop working after couple of days the phone screen start getting blurred or buffed nothing is clearly visible on screen. Since under warranty period I went to nearby service center but they refused to repair under warranty demands extra charge they said that the phone is physically damaged and is not persistence in warranty.since it has minor broke and this problem arises now a days whereever my phone get fall from couple of month ago .I also contacted customer care many times but they didn't reply till now.so I request you to take action effectively to resolve my problem.