Friend problem? wut do i say bout it??? please help!?!?!?

ok so today is saturday. last saturday i told all my friends not to make any plans for the next saturday(which is now today. i was gonna have my mom pay 4 all my frans to go see alvin and the chipmunks). and i specifically had called her and IMed her. she said she wudnt make any plans but shed have to call her mom. so yesterday im talkin to her and she says she mtie be able to come but one of her frans was in over. she told me she wud call me wen she found out if she cud come or not. so today she doesnt even show up. i was suuuuuuuper mad bcuz i had specifically told her not to make any plansand she did. she made plans during my movie party. im extremely mad at her but i dont kno wut to do. i was already thinkin she was beginnin to become a bad friend. tell me wut i shud do..pleeeeeease!!!! :( like i mean she didnt even call me to tell me she ***** come...