To avoid any extra costs when using metered connections, you can disable the synchronization features of Windows 8:
- Update of live tiles.
- Synchronization with SkyDrive
First your will need to define your metered connections: Set network as metered connection
Next, you simply have to disable synchronization over metered connections:
- Open the Charm Bar (Windows + C)
- Click on Settings > Change PC Settings.
- Scroll to "Sync your settings".
- In the right pane, scroll to "Sync over metered connections".
- Toggle "Sync settings over metered connections" to "Off".