Sometimes it's easy to exceed the limits of your data plan without realising it. But there's a way to avoid surprises. You can set up usage warnings so you know when you're close and set up hard limits that turn off mobile data so you don't go over your limit. Some apps transfer data in the background, when you're not using them; you can restrict background usage for these data-intensive apps.
Go to Settings > Data usage.
To set the warning level, drag the right-hand side of the orange warning bar up/down.

When your data usage reaches the specified level, you'll receive a notification.
To set the usage limit, select Set mobile data limit. Then drag the right side of the red limit bar up/down.
When your data usage reaches the specified level, your phone will turn off data usage.
global-en-gb-en-gb-3213-444 2015-04-14T14:59:42