MX Road Volumes

I've never had to do this before and struggling to achieve this - and I've got some time pressure....

I have a road design for an access road through a steep site.  I have 4 strata levels defined as surfaces within the project.  I've managed to get the earthworks cut with a defined gradient depending on the strata (although not without some errors, failing to recognise where it should finish).  But how do I output a cut/fill volume for each of the individual strata levels?

Comparing the proposed / existing for a total volume gives me one answer.  I've tried varying options of volumes but I can;t get any answer that seems comparable to the total volume (that should be the correct one) when I compare it.     I feel I need to volume the existing surface and the individual 4 level but only against the design extent at that level.

stumped.  Thanks in advance for any help