My IPhone says I don't have enough storage

I'm trying to download a movie I bought off of iTunes, but it needs 3 gb to download. I deleted every app I had, and erased 900 pictures. I deleted all messages and some music. When I go under settings and usage it says I only have music and video taking up space. But, neither are even a GB and it says I have used 4 GB. I already purchased the movie and have no other apple device, Help

Restore it to factory default (save all music e and pictures) then add it on there

Try deleting other videos you already have and you can but the movie in dvd or blueray form pretty cheap probably or just wath it online for free?
why are you going through so much trouble for a movie?

Get a bigger one

1:delete what you want to delete
2:turnoff the phone and sweach it on againe
3:try to downloade againe
wish it works