Shawn,
I can see why they didn't want to bother sending them to you. The material seems to be almost clear in the center of the plunger, then goes almost opaque at the thicker parts. Not that there is particularly anything wrong with the appearance, it's probably just not very close to what you sent them as a sample.
Something you may want to try:
Get some white Krylon "Fusion" paint. Spray some in a bottle cap, or similar receptacle, until you get a puddle in there. Pour out a few drops into the plunger and swish it around until coats nice and even, then dump out the rest (don't let a puddle dry in there...too thick)
This will give you the diffusion you need, where you need it, which is at the back surface of the button rather than the surface of the LED.
You could also try to find some thin (10mil or so) white plastic film and cut a circle to fit inside the plunger.
RandyT