My parents want me to cut my hair, but I don't want to!?

im female. we live inside a hot place so my parents always care alot and they're like how can u stand tht hair it's so long and it's actually like not tht long, around two inches below my shoulders. and we're going to visit my grandparents who are very old fashioned and my parens say that theyre going to get mad about my hair. but i really really want to keep growing it longer. but i also want to get a perm and bangs, which my parents have already agreed to. but now tht i said that i don' want to get my hair cut shorter, what if they don't let me get a perm? wat do i do then?