Has any one experienced battery drain issue on lumia 620? Cause i think battery of my device drains very quickly. Hardly 4-5 hours. I use whatsapp, play games i guess for half n hour not more than that. Second issue is wifi its too weird. When i connect to a wifi after sometime it gets disconnected automatically. So i have to everytime go to settings and connect it again. Tried hard reset but that also didn't help me. Help please