Consumer Redressal

I have ordered micormax phone from online mobile store on 06/11/14 and i have received the phone on 14/11/14 with billing date of 7/11/2014. when i checked the phone i found that the rear camera is not working properly. i reported the same to the mobile store cce and ask them to replace the phone. They asked me to visit micormax service center and ask them to provide DOA. when i visited micromax center they said that they can only issue DOA within a weeks time of billing date. they also said that the camera is defective and it will take 20-25 days to change the camera. I again called up in the mobile store helpline but they simply denied to exchange the phone without DOA. Now why the hell the mobile store asking for DOA to exchange the phone if they can't deliver the consignment in a weeks time. kindly help in replacement of the phone.