645D dust removal and sensor clean

I'd be grateful for any advice on dust removal.
Has anyone had persistent dust on the 645D sensor?
What methods have been used to remove the items?
Has anyone had to return it for cleaning and who did they use?

thanks
Paul

After my Arctic Butterfly failed to move the dust, mine cleaned up fine with visible dust 33mm Vswabs, corner swabs and VDust Plus fluid.

its actually very easy to do.