I posted a while back about my dealer replacing my 01 lights with pre facelift, but then correcting the problem when I brought the car back, although unrelated to your question.
Unfortunately, unless you know someone at the dealership that you can nugde into hooking you up, I can see how they may be required only to give you the appropriate year lights. I can't see the facelift lights costing "that" much more, if any to produce, so maybe you can offer to cover the difference in cost?
MB has probably planned on manufacturing new tail lights for only the set amount of registered R170 vehicles currently on the road, and as a result can't start issuing the facelift lights to the non facelift OEM vehicles.