I tried something similar. I had 17.5L spent in 6 months on my Amex Plat. I have HDFC Millennia LTF with a 4L limit which has very minimal or no spending, the CL on it was increased to 12.3L in July 2024, after which I wrote an email to CC, the Credit Card team, Grievance redressal team, with the Amex Plat spends, salary slips, and also tried threatening to remove all FDs, accounts held by the family, etc (total value of 60L). But they did not budge and declined to give Infinia. My RM, BM & CC person in my home branch was getting screwed by the bank since they did not want to lose a customer, but still, they did not approve Infinia.
My RM said she would try to get approval from the executive team, and explained there is a process for them to get exceptional approval but it takes 3 months. Also, my balance is not high in my account, I had the "Preferred Banking" tier, and recently, with an even lower balance, I got upgraded to the "Imperia Banking" tier. (I could not understand the logic behind this unusual upgrade)
After looking at all the nonsense from HDFC, I have decided Infinia is not worth it now, I will not be pursuing it anymore.