I have 15 months old MoneyBack+ and I am preferred customer (it doesn't matter ik) but they mention "Premium Cards" within their brochure for preferred so I think it should a bit matters.
I never got LE in this past 15 months, tried not spending anything for 6 months, and that too didn't trigger LE.
I filled the upgrade form and ticked Millennia along with LE and sent it to
Grievance.Redressalcc@hdfcbank.com. They took the request in first go and didn't ask to send documents offline.
Almost 7 days later, they told they can increase only by 60,000 making the overall limit to 1L as it is 40,000 currently. However, today I can see the 1L is reflected but no Millennia upgrade is shown within cards.
My highest limit is 4.2L reported on CIBIL, also hold 2.3L Amex MRCC with same payslip.
HDFC is just being egoistic I guess.