Zerodha charging penalty charges for fno for no reason

Zerodha has charged me penalty charges of 1500 rs but I don’t see any reason for it, also along with margin there was free cash available all the time.
And how do they calculate this, since i had positive freecash with me all the time, is this fair also.

A post was merged into an existing topic: Bought options on Monday, sold on Tuesday, after which I bought options immediately and got charged a penalty, why?