@Manan Surana I use ICICI ASBA and lot of allotments considering many accounts! Sorry i don't use national bank and not fan of it due to down time, low management, late unblocking, slow outward, less customer support and fan of bank+demat together like ICICI.
[OFF TOPIC BUT SUGGESTIONS]
The best demat - ICICI
Best management and user interface - ICICI
Highest charges - ICICI/HDFC/all banks
To make lower charges in ICICI - Subscribe to neo prime (life time plan)
Use ICICI only for IPO, use low charging demat if you are doing regular trading or secondary market.
Please plan according to have it!