Problem with data traffic charge

[Vexaah]

Hello everyone, I have had this problem for a while now. I've noticed that data charge applied for dozen of times and it's wasting pretty much all of my money that I put on SIM card. I've tried everything I could. First I assumed that mobile data turned on itself but no, that part is okay. Then I thought maybe I have some apps that used mobile data spontaneously which would then charge me so I turned off background usage of mobile data and the problem remained the same. The last thing I did was factory reset my device and problem is still here. Maybe it's not a problem in device but at least an advice would be helpful. Thank you. 

[Qatrium]

@Vexaah

You can fix this by disabling one setting in Developer options, and to enable this menu, you need to go to Settings > System -> About phone -> Scroll down to Build number and tap on it 7 times.

Once done, go to Settings -> Developer option -> Scroll down to "Mobile data always active" and disable it.

[Brackwater]

I'm experiencing the same problem. The "Mobile data always active" option was turned off by default in my case.

[Vexaah]

Mobile data always active is turned off by default in my case too.. If you come up with any other solution let me know. Thanks.