eTrex - missing roads

I know the base map is intended to be _very_ basic but I'm amazed at the
number of seriously major roads which are missing.

On a recent trip "oop North" I was surprised to discover that my eTrex
Venture Cx thinks the A449 Wolverhampton to Stafford road terminates where
it meets the M54. The section North to Stafford wasn't shown. It's not
just A roads. Even motorways are missing. The North East quadrant of the
M60 around Manchester is conspicuous by its absence.

OK, I know it's only meant to show main routes and major towns but these are
major arterial routes.

Keith