Illustrator :: Modify WMF Graph Generated By Statistical Program (make It Look Nice)

How to edit a .wmf file that is a graph and was generated by a statistical program. I need to visually enhance this graph, making  it look more appealing for publication in a manuscript. It's very simple, just need to make rectangles behind the existing text  that form the columns in the graph, and shade the rows of the graph  to assist the reader to follow the row across the graph. While I can edit the text on the .wmf, I can't get a rectangle to be placed under the existing text unless I lower the opacity of the rectangle which won't work as I need black and white only.  I've tried converting the text to rectangle, but the stretching of the text won't be acceptable.  What would be the workflow I should attempt to follow to enhance the looks of the document in illustrator?  Is there a trick to getting the rectangle to behave?  It works just fine if I actually type NEW text in, then place a rectangle, but I'll have to work with the info in the .wmf file - can't re-type it all.