That's never gonna match. I'd raise all kinds of hell!!

 

You can have a difference in color when painting on one substrate to another. You see this alot in color between plastic bumper covers and metal fenders/quarter panels.

I will say, however, that is very far off. There are always variances in paint color. This is why spray out cards should be done to verify you are using the correct variance of that color.

Did they have your truck in the shop when they painted the cover? If not they were basically taking a shot in the dark for the color.