I think AZ doesn't use 6540 for GC Purchase which is why we still get 5% CB on Millennia
As acc to T&C,
5% CashBack on 10 Online Merchants – Terms & Conditions
- A cardholder will be eligible for 1% CashPoints on prepaid card/gift Card/ wallet load and / or voucher purchases. All the transactions carried out through the Merchant Category Code (MCC) of 6540 (as defined by card networks Visa, MasterCard, RuPay and Diners) will be considered under 1% CashPoints even if it is from the 10 online merchants.
So, enjoy till it someone from h*fc notices it (or someone lets them know about it)
😛