The best way to fix this unusual situation is with a little bit of heat, a straight edge and some clamps.
- Clamp the warped piece to a straight edge of some kind (wood or steel) to remove the bend.
- Place the warped piece in a flat cooking pan.
- Pour hot water (160 - 170 degrees) into the pan deep enough to completely cover the plastic.
- The heat will allow the plastic to "relax" and naturally straighten out.
- Leave the plastic in the hot water for about 10 minutes so it gets completely heat-soaked.
- Remove it from the water and remove the clamps.
- It should remain straight on its' own now.