HDFC Bank — HDFC Bank - Net-banking Issue - high severity memo present on debit account

My HDFC account has been locked from the past couple of days. I recently changed my address in my profile - after which I received the following message -

"The address change letter for HDFC Bank Customer ID x412 has been undelivered. Please visit your nearest bank branch urgently to avoid a block on your account."

And to my surprise this block has happened in spite of the fact that there was no attempt at delivering any letter at my home.

When I went to the nearest bank branch, the branch official could not detect the issue and kept saying my account is still functioning. Upon contacting Classic phone banking - I was informed that the account has been closed due to - "high severity memo".

I have been an HDFC bank customer since 9 years now, and having to face such kind of issue where I can not send or receive money is frustrating and pathetic - and this has happened due to no fault of mine.