NDTV — Networks problems

Address:	New Delhi, Delhi, 110074
Website:	www.ndtv.com

I purchased era HD and open the box on 20/11/15..Vodaphone SIM used its working well but from 12/12/15 2g not working ..I tried so many times but on 2g not working .I tried so many trails as I could but no use. The same sim 2g working OK in other mobile on same place. finally I change my sim card and reset the phone to factory resetting. Even though there is no use. I'm very disappointing barely in 2-3 week time the phone becomes headache to me..