I need to pick my little girl up from school this Friday from school but they have put me on a late ..... I’m sick of my boss letting everyone else go see there kids early but when it’s me they don’t

I’ve never had a day off work been there over 2 years as well .... got no one to collect her, what can I tell my boss ? any advice anyone. I just am sick of them taking the **** out of me now ! So anyone who is clued up on this let me no as I am going to work shortly. people in work all the time say to the boss got to leave early to get the kids from school ect ect I just don’t no what to say as I am too nice and soft and feel like there taking advantage of me now