Dude I feel you pain brother.
I had exactly the same issue you today with my UPO rubber strap that arrived from Josh this arvo.
Took me nearly an hour . Put a screw driver through my index finger lots of blood which was nice
First swap the spring bars over top to bottom, I really noticed that helped with the top strap. You may even want to get some thiner spring bars from a jeweler.
Try to put one side in first and then I went in at the top with a really small screw driver 1.6 or 1.8mm , so I had teh watch dial up , one pin in and then worked it down from the top.
Hope this makes sense, if you cant get to work, find a rep friendly watch smith, lot less pain
ST4