Niki.ai — receive used amazon gift card

I purchased 3 amazon gift card of rs 2000 each from niki but when i receive them and try to use them they show that they are already redeemed. I try to contact to niki executive several times but no response till now. I need my money back or give me amazon voucher worth rs 6000 which are unused. It is a fraud with me. I have also put this complaint on twitter handle of niki but no resolution till now. If my problem is not solve i will go to consumer court