To solve this problem Facebook is partnering with more than 18 operators in 14 countries. You can know the countries and operators HERE. According to Facebook, they offer free or discounted data access in coming months for Android and iOS Messengers, Facebook for every phone which is optimized for chat.
How to use Facebook on Android if you have Low Bandwidth Connection?
If you don't like to use any apps, simple way to reduce your usage is to change the settings of your browser in your mobile device to low features like reducing image quality, loading only some portions etc. It will reduce the data usage to some extent.
If you have any ideas or apps for reducing data usage, please let me know.
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