After asking HR three times to approve my time off request for my college graduation, I have been scheduled to work the weekend I graduate college.

I know I can call out or tell them that they've scheduled me on one of the most important days of my life and to PLEASE change it, but after ALREADY visiting my store's HR THREE separate times to tell them accept this request I made at the beginning of the school year and them doing absolutely NOTHING about it, is there a way that I can report this to THEIR higher ups? The request was NOT accepted, NOR was it denied in the system. Can I report their inability to do anything about it or call some sort of hotline about it?? Thank you!