I had used Airtel, Tikona & Reliance, all three are BIG SCAM. Customer service is good but product is worst.
Compare those brand with BSNL, it is far better. In terms of speed, signal strength & connection status. I had never gone through the trouble of slow speed or no connectivity. 100% value for money.
Customer service is poor but that maybe during initial phase like getting the connection & installing. Rest you would be happy & smiling.