Let them know that you won't take it. Stand up straight, tall, put your chest out, look them in the eyes and with a strict voice say "Don't ******* touch my shoes". Tell them, say "man i just got these unless you wanna buy me a new pair i suggest ou grow up". If they do touch them again, you slap the sht out of them. Otherwise, if you allow them to continue, they're gonna do it more and more because you'd be considered a little btch. Stick up for yourself and you'll be fine man.