Consumer Redressal

I bought a Samsung Galaxy S Duos on 13 March 2013 and within 3 months it had a fault and since it was in warranty i took it to the service centre located at Ajrondha Faridabad to get it fixed which they did after 3 days and the again after 20 days the same problem appeared and then again i took it to the service centre and it took 2 days to fix it and now not even a week has passed the problem has reappeared. I want replacement of the phone.I have the bill as proof that my phone is under warranty. Its really frusterating.