brokerage minimizing ..

#1
Hello guys,
So far I have been trading through icicidirect in cash segment and fno segment...
In the recent 2 months, i have been trading in fno on intraday basis which ususally consists of dealing in 2 nifty lots,trading only once a day, rarely i go for multiple trades of nifty when there is a strong trade signal.

Now few days ago i opened account in sharekhan, and selected 7paisa per 100rs plan. I will be changing it to 5 paisa immediately for which i will have to give another 4k to them (refundable). Icicidirect also charges 5 paisa for fno.

What I want to know is based on my trading volume, is it possible to bargain the brokerage rate below 5 paisa? If so, then upto how much is it possible.