Flipkart — flipkart not refunding money to gift card back

Address:

Bangalore, 560037

Flipkart is not returning money to my gift card if I return some items. They just eat it up and when I call the customer care they just blubber something as if they dont have proper training. Not sure how a company like Flipkart is cheating customers to such extent. I would like to sue them . I have necessary proofs

Till now I have called the customer care hundreds of times, still the issue is not resolved. they just say that they have credited amount to gift card/wallet . however when i see my wallet, money is not there. I also tried adding all my gift cards to flipkart back again in the hope that somehow the money reflects, but in vain

They are a big cheater in the name of E- commerce. Please let me know how to sue them