HDFC Bank — HDFC Bank Account blocked due to address change letter undelivered

I received an email saying that my a/c is blocked due to address change letter undelivered. Below are the sequence of events which I tried to get my account back.
1. Called customer care and they suggested to visit nearest bank
2. Called my RM, she said she will send an email to concern people and will keep me posted. Till today she is not responding to my calls
3.Sent an email to [protected]@hdfcbank.com with detailed information on the issue. No resolution yet.
4. Sent an email to nodal officer. No resolution yet.
5. Raised complaint on website. No resolution yet.
6. Visited nearest bank and explained my issue. They had no idea on why there is block on my account.
7. Submitted a written letter. No resolution yet.

this is the worst experience I got from HDFC. Pathetic service. Even managers have No knowledge on their own bank services. Don't call yourself as national bank. I am lost while trying to get my account back.