i've had this discussion a million times with people in PK, and every time i've proved shahnawaz wrong. main reason is that they know nothing about the products they sell. Same case with any MB dealership in the world, the sales staff will know nothing about the product, just how to sell it.
I can assure you many pakwheelers know more about hondas, toyotas etc than the dealers here or even abroad. same case with mercs, I used to co-host 2 of the largest MB sites on the net (still co-host one of them)
Still, it's possible that this item is part of a styling package, but i can assure you an avantgarde and AMG grille will have the same part number. BTW any merc built after 1998 can technically be called an AMG if it has even 1 factory fit AMG part in it (even a set of floor mats).
Please note that i only wrote that for your knowledge, not to make a mess of this post. I really like the car and in no way am i saying anything bad about it.