Airtel India is by far the worst company I have ever had to deal with. They continue to bill for months after I terminated the service. They bill incorrectly at least half of the time. The customer service representatives are useless - they can't do anything but lodge a complaint. The email system stinks - they may email back, but they never resolve the issues. I have had nothing at all good happen with this company. They have been absolutely the worst service provider of any kind that I have ever had to deal with. I am glad to be rid of them.
They seriously need to revamp their system to be more customer friendly. It's horrible.