Good to hear you got it all good in the end. Did you send it to the same service center every time or different ones?
For me they told me that dirt in the viewfinder (which was never there but got there during the service) is normal - "it's not dust proof". Plus lots of dust in the mirror chamber (not even sure about the sensor - will try out of focus image tomorrow to see how bad it is).
And then the focusing issue. That doesn't seem to get resolved for me Does your camera focuses well with all 3 groups of sensors? My center sensor is completely screwed now but left is better
I'm thinking about shipping my camera to a different service center. Maybe that will make a difference? Not sure...