Currency option charges in Zerodha

I was of the impression that currency options charges in zerodha was 20/- or .03 whichever is lower. But in today’s contract note I was charged 80/- for 4 orders even though total value was around 1000/- only. Did they change charges? Could some one help me with how charge is calculated?

It has always been like this, Rs. 20 per order.

Brokerage is charged on Notional Turnover (Strike Price + Premium * Lot Size).