If i insert a new heading into my document, say at position 5 of 16 headings, the bullet point numbers underneath all the headings in the body text from Heading 6 body text to Heading 16 do not update their numbering in line with the new heading number. i am having to do it manually.
there must be a way to link the bullet point numbers to the heading number allocated, so if i add a new heading into the middle of my document the bullet numbers update.

I take you're referring to outline numbering, rather than bullets (eg •) as such. The number re-start parameters are set via Format|Bullets & Numbering>Outline Numbered> Customize: (More): Restart Numbering After. Ordinarily, you'd want every level except '1' to re-start after the level above it (ie 2 re-starts after 1, 3 re-starts after 2, etc).

So essentially what you should do is select some content with the Heading 1 Style, then use the above process to ensure all the levels belw it have the correct numbering & re-start setup.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]