Wifi is switched on, rarely use mobile data. Thats always been the case. Someone else in the house also has the same phone (well, technically my old phone... same model) and theirs doesn't switch off. They are on wifi too. :-/
Yea, unfortunately they can end up costing loads and I'm having a very poor moment after a £1000 bathroom issue. I've reset the other phone, using a broken screen S4 now. Reinstalling everything is taking time and battery life...still hours later installing updates so no idea if it's sorted the issue. Taking 3-4 hours to reinstall stuff and have lost my banking login/still app... I may just hide under my bed for a couple of days.
Bah, initially failed, kept restarting again but wondered if it was broom redownloading things, probably didn't leave it too long... I'm impatient, hehe. Will try loading it again and see what happens, maybe resetting again with no reuploads for at least three days.