Flipkart — Refund rejected

Address:

Kurnool, Andhra Pradesh, 518301

I ordered samsung galaxy a7 mobile in flipkart to gift my brother's birthday. I received mobile two days before. I opened that box in bluedart courier office in that box there is mobile box but in that mobile box there is no mobile. The box is empty. I asked flipkart for refund they accepted and told me that they will refund amount with in 5 business days. After 5 business days again i called flipkart they said wait for 3 more days you will receive your refund i waited for 10 days i didn't received refund again i called flipkart they told me that they will arrange replacement. I rejected that replacement. They again accepted to refund my money again i waited for 8 days. Now they rejected refund. What should i do now. Should go for legal fight?