even if connected to wifi and disabled mobile data but still mobile data being used

i am facing a very serious problem i my moto g 4.4.4.
the problem is i am using WiFi connection and disabled the mobile data but still at regular interval my mobile data is being used in some app and my balance got deducted.
as i don't have any data pack which cause a huge amt. deduction.
even i restricted background data but nothing worked.
please suggest me to overcome from this issue.
your solution will be highly appreciated

Go to settings - Data Usage and check which app is using mobile data. If you need extra help take an screen shot of that graph and apps list and post it here.

Are you sending MMS?

I'm having the same exact problem, there are at least 10 apps that have consumed some internet data, not much, but mind you, it's sufficient to see a small fee on the bill. By having Internet Data disable and no background data allowed it should use ZERO internet... only thing I haven't tried would be disabling autosync but that affects WIFI as well and it would suck big time.

I'm on a Samsung Galaxy Tab S 8.4 and Android 4.4.2...

Have you found a fix to this? (or does anybody know?)

Thanx!