I tried to check my email earlier today and my bloody phone said "Delayed Re-write" and decided I couldn't write to my phone memory.
Result - all my messages deleted.
No problem I thought, I'll just restore to the backup I made last week. I specifically told my phone to restore just the messages. Although it said it was restoring and wanted a restart, no messages were restored.
Backup function is useless if you can't restore.
BAH