Airtel — all lines are busy error in airtel

Address:

Kurnool, Andhra Pradesh, 518003

I have been in airtel network for last 6 years but now i think it is the time to say good bye to airtel.
I have to dial a number multiple times to connect to a particular number. It says that "all lines are currently busy, try again later" and sometimes call automatically gets ended without any sound, called customercare as well, the only solution they will have is switch off and switch on the device and i know its never gonna work coz i have tried everything. It really irritates a lot when you are really in hurry, and make a urgent call but your call could not get connected.
I need to carry a extra back up basic phone with idea or vodafone sim in it.
Waiting for response...

[protected]
Narayan sharma
Airtel ap&telangana