@situmin - 250 mb can be sucked up pretty fast if you keep your data toggled on, or have settings that are using it in the background.
The usage details for data are about 6-12 hours delayed so check there now, and then again this evening or in the morning. It may show you that you already used it all up.
250MB will replenish when your plan renews again. You may also be interested in purchasing data addons to keep on your account. These will only be used once plan data is exhausted each cycle, but stay on until all used up.