Note 5 use roaming data even when it's set to off

Hey all, my note Note 5 is model SM-N920C and running on Android 6.0.1. And I have this problem where my phone access data when it's roaming. I have set Data Roaming to off, and last trip I have even set the Data on notification area completely off. But I always get billed lot of money for...

Note 5 use roaming data even when it's set to off