I was NOT aware of that "high" STT charges, what I was thinking that it will be around 50-100 or 200 Rupees for my In-The-Money Option (16 Lots) on the basis of total transaction value that was only around Rs 18500/=..... All I can say... is..... my profit vanished and I took no loss.... I am happy with this too..... but for STT "very very high" charges, this is NOT a good practice that NSE is applying...... Zerodha only flashes a message but Zerodha does NOT "tell" in the message how much of these charges "could be"..... anyway....... it happens.....
There is a link in this bulletin from yesterday with the details of how NSE charges STT. Bad luck, but maybe if you had read the bulletin, you could have avoided this. Hope this helps for the future.