My Micromax Canvas A102 mobile which is under warranty cannot be repaired

My mobile Micromax Canvas A102 has stopped working since last 15 days, I gave it to the shop from where I purchased it, for checking, namely Namma Mobile, Near City Bus Stand, Udupi, Karnataka. The shopkeeper is saying that the battery needs to be replaced and will be charging me for that, but when I told him that the phone is still under warranty, he replies that battery has no warranty, While purchasing the mobile they did not mention this, I dont understand what is covered under warranty. I request you to please help me in getting this phone replaced, I am ready to pay the price difference if the company is replacing it with a new model.