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Go to settings, network, cellular data and turn it off. Only turn it on for the limited time you need to use data and can't find any wifi.

That limit will be really, really hard to not exceed.
 
Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A406 Safari/7534.48.3)

I have no choice, I still have to listen to my parents, so I'm going to start persuading them on letting me buy my own plan.
 
Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A406 Safari/7534.48.3)

I have no choice, I still have to listen to my parents, so I'm going to start persuading them on letting me buy my own plan.

If you seek work then it's out of their reach anyway. You can earn money and spend it on an iPhone plan wether they like it or not :)
 
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