How can i get rid of rain stains on my ugg boots?

so i was walking home from school & it was pouring. my chestnut UGG boots got completely soaked. i let them air dry but i seen some stains. then, i sprayed them with some rain & stain repellent but the stains still stayed. i'm scared of trying things i've read online because i just got them this christmas & it was only my fourth time wearing them. what can i do that'll actually work?! please help!!