how to change a Graphic ContourPolyPolygon

Hallo,

I Trie to preserve the Graphicobject ContourPolyPolygon after i changed 
the Graphic behind this object. The original Contour is still there but 
with the size , position off the old Graphic.

How can i using BASIC, change this ContourPolyPolygon also named " 
::com::sun::star::drawing::PointSequenceSequence" and adapt the contour 
to the new size and positions of the underling Graphic ?

Thanks for any hint.
Fernand