I have been connected to Airtel since 2009 and I have only problem with gprs speed and apart from that coverage and billing plans are good. Since last year I am sick of complaining about gprs speed issue every week I guess but still there is no solutions and customer service seems not serious about their responsibility.
I have been suffering of 4 to 15 or 20 kbps gprs sped constantly since year long while company claims 60 to 80 kbps and every time customer care executives, super wiser, avoid customers by fraud complements for permanent solutions. I finally migrate to Vodafone forever!