Punjab National Bank [PNB] — debit card not working on online transaction

I have been complaining about my issue with pnb's complaint and care departments regarding my debit card not working for certain online transactions. Initially they responded and asked for some further details and when i submitted they turned mute. Its been a month now that i have been regularly trying to get something out from them to let me understand the reasons or enable me to do the same but i guess all they are good at is keeping mum and keeping all to themselves. Being a customer i have full right to know what is wrong with card and what can be done.