I had a similar fix. I bought a seat cushion from Menard's - in the hunting section. It is made of a firm foam similar to a wrestling mat. I put it on the back of the seat. It had a loop and Velcro strap I strung to the back of the seat bars. It pushes me forward in the seat about an inch and I don't feel that bar anymore. I cheap seat cover is next to make it look better. For less that $6 it at least fixes the comfort issue.
I had a 2000 Contour and the seats were so great- I wish they would fit the Focus. It is my only complaint with the car. I tried other car cushions but they did not fix the issue. The key was to push my butt a little more forward.
I have the 2002 Wagon FYI. I don;t think it is a bar that is the issue, but wear the seat seam is.