Lava Mobiles — my handset lava x41 plus has network problem.

I am using lava x41 plus from last 1 year but i am un satisfied with it. I have checkup my handset two times but there is nothing improvement in it. It has network and calling problems. When i use net sometimes it does not work. It show on display your internet connection is off. Sometimes when i used to call any other then it disconnect again and again. Sometimes it shows network error although others handsets work on that place very successful ly.