How to get refund on mob. Pur. Within 7 days

Dear sir/Madam, I had purchased two videocon mobile - Delite 21 from Yash mobile, Surendranagar, Gujarat on 20-02-2017 . IMEI NO. 911546851050088 911546851050096 IMEI NO. 911546851491704 911546851491712 To gift my mom and dad on their anniversary on 21-02-2017 But there was manufacturing defect in mobile, in 1 mobile there was speaker defect, no ringtones or song could be played and both mobile got heated very much. So we contacted service center in Surendranagar , after visiting service centre many times we received DOA. I have submitted DOA. Now we want refund of both mobile phones but shopkeeper is not ready to refund money at all. He says that he will provide same model which he has received from company. We are now not interested in buying this mobile anymore. I request you to do the needful as soon as possible. Please Reply On Mobile Number :-8264783401 9067924171 Or On email address :- dvshah1988@yahoo.com Or Shahkrima6553@gmail.com