Edit: Just realised this is you John - finally able to join
you know the below now but I'll leave it or others in case they like the reference info
Welcome aboard! Lovely colour (loved my TR GTI)
In regards to your rear handle, basically why happens is that the metal that the early badge was made of gets water under the top layer and corrodes - hence the whiteworm. The badge is stuck to the base with double sided foam tape. You cannot buy new versions of this badge.
Beginning about 2006 VW changed to a raised VW 3D badge style handle where the badge is plastic and clips to the base - much better. This badge is not backwards compatible (without a lot of effort) with the earlier handles. On the mk6 golf the raised badge changed designed a little to have beveled edges.
There are a few options for you
1. Take handle off car, remove the badge, sand down to get rid of whiteworm, wrap in vinyl of your choice, reattach
2. Take handle off car, remove badge and sand down, then spray how you like
3. Take handle off car, replace with a later raised mk5 3D or mk6 3D complete handle - either standard silver or customise with vinyl on the base and or the 3D badge - or spray base
Hope that helps