Airtel — Network issue voice drop

I am using Airtel service over 10years and moved from one part of Bangalore to Kundalhallai area. From day one I am facing voice call issue, almost 40% of the day my phone shows no network connectivity. I tried 121/198, can't understand the message. Airtel Advertisement shows it reaches even in dense forest, but within Bangalore urban area itself we face such issues. Its not only me, entire community here has this issue. Also Airtel site does not has a sepearte space to lodge complaints.