Thanks for gettting back to me Stefan. my heading 1 is based on no
style and the subsequent headings based on the one before.
Automatically update is not ticked in any of them. It seems to happen
most often to heading 3. Is there a setting a user can have ticked in
their options that enables them to update styles when they apply direct
formatting. As I mentioned before - it seems to be that they apply
director formatting, then this sticks to the style and it applies in
that format each time they use after that. By the time they contact me
the damage has been done.