Studfinder (metal detection type) should locate the metallic components

Are you 100% sure it's even there? I wouldn't trust it being there just because the plans show it is.

If this is a new house and you are 100% positive that it is there and the carpet layers covered it, I'd call your carpet layers back and make them uncover it. It's their fault.

But like I said, I wouldn't trust it being there just because the plans say it is. Things change and most of the time plans aren't followed 100% to the letter.

Do you really need the receptacle? We had one in our first home that we covered with an area rug and never used, and we have two in our current living room. Both are under the sectional sofa and we don't use them. I suppose if we put an end table by the sofa with a lamp, they might come in handy.

Like hexus said, if it's a new home and the carpet people covered over it, I'd make them come back and fix their mistake.