MacBook: Getting black... unfortunately

I purchased my MacBook when Apple first released them. At that time I chose a virgin variety -- well I mean white.

Removing the plastic part is quite easy as you have small clips around the screen. Unfortunately where to buy that stuff?

And I've been happy with Angelantonio for months now -- yes, that's "his" name, from my great great-father firstname. I use it daily.
But recently, I've noticed this unpleasant discoloration at the very locations where you put your hands around the keyboard, on the track pad but also around the screen!

Though I clean it up almost daily, those marks does not disappear and won't never I'm afraid.

I knew early MacBooks were suffering from discoloration and that some US Apple Store was simply exchanging them if you were returning your Mac.

As I've purchased mine form the Apple Store I called a Maintenance Center in order to see if by chance such a plan was actually set up.

I then called (many) maintenance center here in Paris, France, asking for whether it was possible to purchase the two small pieces of plastic that cover the screen and the keyboard, telling them I will do the replacement myself.

Unfortunately, my call ended up with a "I'm sorry we don't sell parts, you have to come to a maintenance center, leave your MacBook for (at least) ten days, and finally we'll be able to say if we do replace the plastic parts and the price for the mainteance." No matter I say I really need my computer to work... That's a pity, really... (Should I say it sucks?)

Some people on the Net say they used a Mr. Clean magic eraser with great results. Unfortunately, I tried this yesterday but it didn't work for me!?

What should I do then? Did someone manage to buy those two pieces of plastic? Tell me...