Paid hdfc cc bill upi via indusind account twice.
Only hdfc cc payment failed for me, may its dcb thats why.
Rest all bank cc were credited within 2-3 days.
They use to offer prosperity account which can be made zero balance if you fulfill any of condition mentioned on form. I selected auto debit of min amount due on card. Don't remember the other options. Not sure they still offer it. Though I don't like their net banking interface.