My wife has an iPhone 5s that has iOS 11.4.1(15G77) installed with the "update" setting disabled in Settings > iTunes & App Store. A few times now we have found our internet daily usage being used up by the iOS 12 update downloading even though she does not get a notice that there is a new iOS update pending and, most importantly, she has not pressed the download and install button for the update to start downloading. It somehow downloads automatically. Id there any setting in the iPhone that we missed to completely disable an update that automatically downloads?