Letsby, just finished this rig ma roll with the HM.
They have allowed:
Change to 2007/08 tax code
Refund for 2006/07: £380.
Back dating to 2002/03 if I have made self assessments in the past (which I have).
Also claimed 'uniform' [shirts/trousers/epaullettes] allowance for certain years.
Keep plugging away at them, it is relatively 'new' to many tax inspectors.
Treat them as you would a CAA FOI(H) - most of them don't know all the rules and ALL of them are out of sync with their counterparts when it comes to legislation
Good luck