Over 30 gb of iPhone storage is "other"

My iPhone is 64 gb and half of that is full of "other" files from Apple or caches. My phone does not delete the caches when space is needed like it's supposed to. I have had to delete my music app and most of my photos just to get by. I feel ripped off that the space I'm supposed to have on my phone is not truly there for me to utilize. Any guidance would be appreciated.