preventing the automatic download and installation of iOS 8

Grrrrr. This needs a solution. I have a portable wifi account I use for teaching (mainly Apple devices) and when traveling. It updates my download capacity in 1gb chunks at $10 each. Just traveling at the moment, and this coincides with Apple updates. Three devices, @ 2 odd gb ea, all deciding to update while I drive. By the time I got the update notices from Optus, all three devices had downloaded the updates and were waiting for me to press install. I don't mind installing, but I don't want to pay $60 for the downloads thru this account. I think Apple owes me $60. There's no reason they can't set a restriction on this type of download for user nominated accounts. This is a significant issue for a lot of people. Please Apple,

turnoff auto update app and make it so you can not download anything on cellular data in the setting got to cellular then scroll down to use data for then uncheck setting and app store

This is a portable WiFi device. IOS devices see it as WiFi, not cellular. Users should be able to have download only on specific, nominated WiFi accounts (Or no WiFi devices, if that's what they want)!

i have never had a problem with an ios update downloading automatically personally