I personally have a Vodafone sim so someone suggested me to buy a airtel sim so I purchased one.
Now using Airtel sim I faced many problems like no network coverage and poor customer service.
I also have a Airtel Wireless Broadband and I am facing problems and when I call customer service they never solve my problem.
I have paid 6 months advanced payment for airtel broadband and it is not working and when I register my complaint no one answers or solves my problem.
Although Billing system provided by airtel is quite good.