Then I synced my phone on itunes and it worked! I can't believe how long I've been trying to fix this stupid issue and I finally got rid of that huge 6.60gb of space under Documents and Data! I regret ever upgrading to ios7 as I never had problems before until I upgraded but I was forced to as most apps required the upgrade. It was showing 6gb of messages (saved) so I went and deleted each message one by one (ridiculous that there isn't an option to delete all messages at same time or at least multiples without having to hit each one individually!) but I made sure to back them up first on this software I have called iExplorer (I think I paid $29 for it but can't remember as I got it so long ago but really never used it until now). I was having this issue and it was driving me nuts because I already have such little amount of space! I followed the advice of someone on here (I can't remember which forum it was) and went to: Settings > General > Usage and I could see immediately that my Messages was taking up all the space in 'Documents and Data' category.
