Filling in shapes imported from a CAD program

Hello,

I hope someone can help. I use CorelDraw for setting up my CAD files for my laser cutter.

I would like to 'fill' some closed objects for laser engraving, but no matter what I do, I cannot seem to fill the required parts.

I think I have uploaded the file with this post, if I have, could someone please look and tell me if it is possible? The parts I want filled are coloured black. It is driving me made not being able to do this!

Thank you,

Chris