I was having trouble syncing my playlist to my phone. I had over 1000 tracks on my phone that I didn't want on there and couldn't get off. I tried un-ticking 'sync music' under 'music' tab, and un-ticking all boxes on the Summary page clicking on APPLY and SYNC but still these tracks remained. I downloaded the latest software to my laptop and handset. I tried restoring the phone from the Summary tab. Nothing worked - my phone still had 14GB of either MUSIC or OTHER that I could not remove. When pressing 'Sync' iTunes would back the phone up but wouldn't sync my music. Finally I had to get help and got a call back from Apple. After 1.5hrs exhausting all possible solutions, I was asked to back up the phone, disconnect it from laptop, go to SETTINGS-GENERAL-RESET and then select second option from top ERASE ALL CONTENT AND SETTINGS. This took a few minutes, and will restart the phone. Once it restarts it will ask you to set up language and wifi connection and if you want to set up as new, or from back up WIFI, or from back up ITunes. You can then reconnect the phone to the laptop. iTunes will recognise the phone and ask you to follow setup instructions and will then set up. If you choose to set up from back up like I did, all the data, apps and music will be synced. Sorted. Finally. I'm so happy apparently this happens when syncing is interrupted. My rep didn't get too technical with me other than saying this memory taken up on your phone is a residue of previous syncs that where not completed. Whatever it was it's fixed. I hope someone finds this helpful.