on paper officially credit card bill payments shouldn't give any reward points, whatever we're getting till now is due to technical glitch, or managemnt of mcc. If you complain, they dfinitely consider it based on number of people reported and take necessary action and may stop altogether if they want.
www.hdfcbank.com
credit card bill payment is not utility. you're going to complain about not receiving cashback for excluded category, if its 🪓 they surely will ask proofs and block entire savings account, if they want (it maynot but for general idea).
understand the pattern and follow the working process silently, do not involve authority.