Although iTunes on my Mac says I have over 25 GB free on my iPhone 5, the phone itself keeps telling me I have zero bytes left. I reboot and whatever but it doesn't help. I saw elsewhere that I need to do a full backup and then restore the phone to factory settings... but it won't do the full backup because, it says, the phone "cannot be synched because there is not enough free space to hold all of the selected items." I guess it thinks the phone doesn't have enough space for all the stuff that's... uh... already on it. So the problem is preventing me from implementing the solution. What should I do?