Apple India — iphone 10

I bought an iphone 10 from shop india. Xyz on 22nd december on cash on delivery they gave me a faulty product and now not taking my calls after i ask for refund please help me. The owner is not even taking my calls and has switched off his phone and not answering messages also i have texted him like hell. His number is [protected] and website is shopindia. Xyz. I bought phone for 12000