Talk to a credit card representative in your branch or write to customerservices.cards@hdfcbank.com . There are lot of discussion threads in TF on how to escalate your concerns.
I faced a similar issue with my times platinum card. They didn't upgrade it. I tried upgrading it through the branch, but it was rejected. I blocked the card and stopped using it for years. After opening a savings account, they offered me a Regalia LTF.