Facebook unveiled a new feature a while back in which videos on your timeline automatically load and start playing. While this can be a nice convenience feature it has become the enemy of people on limited data accounts. This feature is constantly using data in the background to load these videos as you scroll through your Facebook feed. Lucky there is an easy solution to this issue which I have laid out below.
Simply go to: iPhone settings--> then Facebook --> Settings--> (Video) Auto-play--> switch it to Over Wifi Only or Off.
And you're done!
Also Spotify; be aware that streaming music uses a lot of data.