HDFC Bank — Cashback not credited to my credit card account

Address: Gurugram

I have purchased two iphone 11 using my hdfc bank credit card. One iphone i have bought in january and second one in february. It is written that an effective cashback of rs.6000/- will be credited to the account within 3 months or 90 days. Its been 6 months and 5 months. Not even a single cashback is credited into my credit card account. Please initiate the refund asap.