I won't go into any sort of discussion on your maturity because I don't know nor care how you act/are in real life. My thoughts are that your parents have a reason for doing this. Sure, technology is without a doubt one of the most popular types of entertainment, one of the most helpful resources for school projects, one of the most harmful things to be addicted to, and can get you in a lot of trouble. If you've done something to abuse your technology privileges, such as playing video games endlessly to the point that it affects your family's relationship with you and your grades for the worse, or getting caught doing something inappropriate online (probably not, since you have the phone and posted here), then I see no reason for your parents to NOT revoke your privileges.
Plus on top of that, you're a dependent minor and your parents can decide what they think is good or bad for you without your consent. If you really don't like the situation, then talk about it with them in a mature manner without complaining, whining, begging, or [insert annoyance here]. If they say no, sorry OP sucks for you. Either improve yourself from there to prove to them that you're capable or wait until you're 18 and move out and do whatever you want.