Isn’t your iPhone fairly recent?
Have you looked to see how much storage space you have left?
Also, this is the first time I’ve ever heard of an iPhone automatically downloading things.
I think you should call 1–800 MY IPHONE and have them transfer you to a product specialist to get this straightened out.
The reason I’m suggesting that is because if it tried to dl something once, even if you do the hard reset and it sets things right, it may keep repeating trying to dl again if it’s an automatic update.
BTW the call and the tech support is free and they’ve always done an excellent job for whatever problem I had. They don’t outsource their tech support so you won’t find yourself trying to communicate to someone who barely speaks English.
(I would also be interested to see what they have to say about automatic dls. I’ve never heard of such a thing for iPhone. Android, yes, but not Apple. Weird. It makes me wonder if it could be some type of malware.