That should not be a problem with the router in general, but possibly your specific unit.
I would not expect them to offer a second discounted router if you have bad range, since anyone can say they have bad range and try to get another router for cheap.
They will probably address the issue with a replacement though if really something is wrong with yours.
I posted this in another post asking how the range is and this is what I am seeing:
To get to the far outside corner indicated on the image it goes through like 8 walls and 2 windows.