Flipkart — Payment not received on sold mobile at flipkart

I have sold my Mobile at Flipkart Sell Back option, on whihc they are suppose to give Thank you card with value as rs 6750. it was sold on dated 12th of August.

I have raised concern to flipkart about the payment, soon i sold it, but no one bothered to resolve my query and initiate the payment of 6750.

I am really worried about such a pathetic service by Flipkart. Not sure till when i will receive my payment, i am thinking to raise a FIR as theft complaint against flipkart.