Credit card default legal notice

Mahoday Legal Advisor saheb. Namaskar. Due to financials. crisis whole of 2018 I could not pay credit card emi and full amount since August for HDFC. Now I post office delivered a chit saying to collect legal notice which I assume from HDFC as they had warned me by email. I tried to contact on phone I never picked up phone as they insist on immediate payment with threatening. I had to stay away from home from 7 am to 12 night for fear of recovery agents coming to home for the last three month. 1. Should I go to post office to collect regd legal notice: Y. N 2. After reading what should I do. I do not have money to take lawyer help due to financial crisis. So what should I do with legal notice. Should I go to court or bank? or Banks lawyer 3. If I go to bank, if they ask immediate payment what should I do? 4. I can prepare reply to myself in simple language and give to either to court of bank? since I am a writer. 5. I lost job. So the notice first went to old office but I told them not to accept any legal notice since I do not work there.So postman came to house (which is locked) and dropped chit to collect notice from post office. Pl advice. god bless.