PHEW! this was certainly a head test for me.
I have solved the problem. Thanks to DBlanks suggestion.
The main issue here, was I was trying to display everything in the group header.
ie;
GH1 - Customer - July units - UHP units - NON UHP units - Points accumulated.
This wasnt going to happen as i was using the shared variable formulas.
I trnasferred all this data into the group FOOTER, hid the details and GH1 sections, and the sums all add up nicely now. exactly what I wanted.
This report can now be put to bed!
thanks for all your help!
much appreciated.