Looking for study cafe or a place where I can study for 6-7 hours without any inconvenience

I have tried " Cafe 16 Satyanagar" But the experience wasn't that good. Plus they charged me extra 120 as GST for a diet coke. Not reasonable. I want an available place from 8:30 am - 3 pm. Food availability is not at all a necessity. Do help me out

Thanks for the patience