To prevent you using over the allocated data allowance and getting Excess Data Charges please follow the steps below to set up a Data limit and warning on your device.

These steps will also show you what apps are using up your mobile data. If you are finding that some apps are using a lot of mobile data, you can set up Data Saver and select which apps you wish to turn mobile data off when Data Saver mode is turned on.

1. Locate Settings under All Apps (or swipe down from top and select cog icon), then select Connections/Data Usage
    
2. Select Mobile Data Usage and in here you can see which Apps are consuming Mobile Data. 
3. Select the Cog icon in top right corner.
4. In this screen you can set your Data warning, which will just notify you once you have reached this amount. Your data will not turn off.
5. At the bottom select Data limit and enter the limit where you want your data to stop. Currently you get 4GB data included in your plan, so it is recommended to set this to 4GB.