I’ve been rejected by them too when I was younger. Actually I’ve been rejected by: McDonalds, KFC, Lidl, boots, Superdrug, Tesco’s, Sommerfield (yeah I’m old), B&Q, M&S, Morrison’s, various cleaning agencies, more cafes and bars than I can count.
It’s bloody hard to get a job when you’re in school/a student. You’ll get there eventually, don’t put too much pressure on yourself.