Do i have a right to be mad at her.?

For my birthday i want a cellphone from the pawnshop and my mom says ohkay we can get it. But for my brothers birthday she got him black ops the map pack and now their buying a new mappack and she also gave him 10 dollars. But the other day i called and they said they had the iphone and i told my mom and she was like ohkay maybe monday, but now the freaking thing is gone and all she got me was a 20$ pair of shoes, and she keeps saying we will check the pawn shop for the past week and she hasnt even stopped by or called there ONCE, and everytime IIIII call they have a phone i want for a cheep price i will tell her and she always everytime says. "Well its from the pawnshop you dont even know if it works" when she was the one to check the pawnshop for a new phone. And it gets on my nerves cuz i do everything tht she evers asks never ever gets in trouble but my brother trash talks her, cuses me out alot, and plays xbox ALL DAY or hes on the computer ALL DAY. And last year they freaking forgot my birthday