Phantom 70GB of Documents & Data iPhone 6s 128GB

My iPhone 6s 128GB iOS 9.2 seems to have some phantom files taking up storage. I've tried all the tips online and those given in the forums, however, still stuck. Have a look at the screen grabs below. I have no Videos, no offline Dropbox/Google Drive files, etc.

iPhone 6 Storage - see how the top 10 apps consume less than 30GB, however, the phone is saying I am using ~100GB of data? Where is this extra 70GB hiding?

iTunes Mac (12.3.2.35) - says "over capacity by 13.29GB" which is insane. I cannot sync anything to my iPhone now.

iTunes PC (12.3.2.35) - this falls inline with what the iPhone says, however, still a mystery where all this space is coming from.

Thanks