Consumer Redressal

Dear Sir, I bought adual SIM LG 375 from Mobile Central, UG-08, Raheja Mall, Sohna road, Gurgaon on 5th August, 2012 for Rs5000/. One of the SIM slots in the phone is not working and I took it back to the SHOP on 18th of August, 2012. On being told of complaint, the first reaction of the shop keeper was of denial. Then he tried the different SIM cards and realized that one of the slots was not working. On being asked to replace the phone, he has refused to give me another handset and started fidgeting with the device and pulled back one of the plastic covers at the bottom of the phone to which led to development of a crack in it. He has flatly refused to replace the phone and has asked me to contact LG office directly to figure out a mechanism for replacement. The phone is still lying with the shopkeeper as I left their out of frustration. I have a receipt on their visiting card and I also have a bill. Please advise as to how do I get a replacement of this handset. Gaurav G