As user
@007 said, you can also mail
grievance.redressalcc@hdfcbank.com to get a written confirmation from the bank that your card is indeed LTF. If this method is successful, then you may NOT need to spend 50k to make this card LTF. You can also apply for an Add On card on your existing card to make it LTF. Since the Add On card is also LTF, you also do not need to spend a single rupee extra to make your card LTF. But to apply for the Add On card in the name of your family member, that member should also have a savings account with HDFC bank. Otherwise, it will be difficult to get an Add On card issued. You can look into this thread by Sumanta Sir for more details:
HDFC Bank recently updated their terms and conditions for converting a credit card to a lifetime free credit card. According to the new conditions, we get 3 options (for maximum cards) for converting a credit card to a lifetime free card. Credit Card Annual Fees LIFETIME FREE (You've to...
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Coming to your questions, fuel will probably be counted in this spend criteria. So you can try to achieve the milestone by spending on fuel. Apart from fuel, you can also try to pay your Utility Biils(like Electricity Bill, Gas Cylinder, Broadband Payment, etc.) and Municipal Taxes from your card. These expenditures are there in every household. Also, you can try to pay Bills and Taxes of your friends and neighbours too(if possible).
Again, as
@007 said, I think that rent payment is also considered towards retail spends. So you can try to transfer your card balance to you bank account through Cred's Rent Payment Portal. After using Cred coins' offer, you will be charged less than 1% of the amount as the transfer fees. But you will also gain 1% cash points as the reward for Millennia Spends. So you will be in net profit through this transaction, and also achieve the spend criteria to make your card LTF.