Do you think what my parents are doing is unfair?

No hun I don't think it's fair. I think they are trying to keep your grades high so you won't end up like your brothers grades and they care for you and want you to have an excellent future. Try negotiating with them to get your phone back and try talking them into buying you something for graduation. I think if you talk it over with them they might realize they have been a bit to harsh on you and they might give in. Just talk in a normal voice about the situation because yelling won't make it any better. Try saying you will get better on your next report card. Personally I think that is excellent grades so good job on you're part :)