Airtel customer service represents everything which is wrong in India. You will get calls every day for paying your bill. People will threaten you and irritate you purposely. You will write to the nodal officer writing your problems. You will get stupid replies about the same thing again and again without anybody understanding your proble.
People will keep calling you without any clue of what is the state and will go through the story all over again.
While I have no complaints about their connection their customer service will drain you out so much that you will wish that you had never taken airtel.