HDFC Bank — hdfc bank - ipad cashback not received

I had bough ipad with hdfc credit card ending with 5303 in chroma store mumbai on[protected]
As mentioned by hdfc bank offer the cash back 3000 inr would be received into my credit card after 120 days
I haven't received the cashback, when inquired at chroma store they told us to check with bank
Please resolve this issue as soon as possible
I even submitted a complain so far received no response from hdfc bank