I'm a bit confused. Do you see the dust in your actual images, or just when you look through the viewfinder? If it's not present in shots, but is present in the viewfinder, cleaning the sensor will not help.
Since DSLRs are just that: SLR (single lens reflex), you are looking through not only your main objective lens, but your mirror, your ground glass, and the lens mounted to your camera as well.
Dirt in the viewfinder usually resides on the ground glass above the mirror. If a can of Dust Off does not remove it (and be CAREFUL with that stuff!!) then I recommend sending it back to the manu for a thorough cleaning. Alternatively, you may find a local camera shop that specializes in cleanings.
