HDFC Bank — account blocked - been left stranded - credit card

We all know that sometimes we run into some kind of difficulties which leads to the nonpayment of some bills. I have been a customer of HDFC bank since 2008 and I have no other bank accounts. I've also been using their credit card for since almost the same time. I have did transactions worth lakhs on the card and never been at default. If I have been for 2 to 3 months, I used to make sure I pay the entire outstanding with a single payment, and I have done that in the past. This time around, I have been going through some career changes for the past 2-3 months and was not able to pay the min due amount for just two months which would be around 4500 max (includes EMI on a purchase). Their recovery agents started harassing me and there was no end to that. They just keep on calling every 10 minutes. I had told them that I would do the complete settlement of the total outstanding in a month but they went ahead and blocked my bank account which had around 6k plus balance. I had kept it for emergency as my parents are old and sick and I had no other resources. I always use digital payments and when I tried to make a payment at a store, it said insufficient balance. When I came and checked my balance showed minus 16k plus. They had included my balance of 6k plus and the remaining outstanding in the total outstanding of 22k plus on my credit card. In despair, I tried to do payment of 4k+ using netbanking but it said insufficient funds. If they block the account, how can they expect me to pay. i haven't changed my phone number, I have updated my address even after a month's default after I shifted my house. I'm not a terrorist or any fraudster to be meeted out this kind of treatment. I just want to close my account and credit card and end the relation with HDFC for good. It's a nuisance for honest people.