Hmmmn maybe the 3G network is a lot better than 2G and data can flow easily. But am still not sure if 3G selection in network won't change how Airtel calculates your data usage. As choosing UMTS will tell Airtel that you are no more a 2G customer. Don't rely on CC guys, they know almost near to nothing. Lodge a complaint dialing 198 about 2G data rate and see what happens.
Meanwhile I suggest please use and try a few network providers so to be sure there is no problem in device as Flipkart replacement warranty is of 30 days. Relying on Motorola service centre could be troublesome.