Jio — Data consumed without using

For the past two days, I've noticed that my mobile data unnecessary got deducted. I turned off my mobile data and switched off my mobile at 12:18 am and finally on 10am. Without any surfing bigger data consumed app like instagram or facebook or YouTube, my data pack said that I've only 50% or less than left. I've called their care but they said that using Hotspot, watching YouTube or Facebook videos, my data got deducted. I've also emailed them, but they said the same thing. But just using WhatsApp, how did my data get deduct like this? This is clearly cheating.