The tow hook covers you refer to are called "grilles" (p/n 9151509 for the right)at the dealership - right and left, and as Klaus says, they were about $20.(Cdn) when I bought one last year. They snap in (and out, obviously), as happened with my '98 V70. It was bought used, and perhaps I didn't notice, or maybe caused it myself - a crack across the strut just to the right of the licence plate bracket. While getting accustomed to where the nose of this machine is located during parking, I've run the lower bumper trim bolster up on some higher than normal stop blocks, and I guess that's what caused the crack. It's not that easy to see, and excessive flexing in that area might allow the grille to pop out, so I'd pay special attention to this, just in case.
I'm not going to insert the replacement grille until I've gotten the bumper trim redone.
Hope this helps - and I'd be interested in knowing if you find any similar damage on your vehicle.
Regards,
Garth