Regarding Cartier in general and Pasha in particular.

I have become interested in Cartier watches and the Pasha GMT in particular (Pasha C GMT Ref. 2377). I have never owned a Cartier watch. I was told by a watchmaker here in Eugene, OR that Cartier is not serviceable by anybody except Cartier. Is that true? I looks like some are powered by ETA movements and that doesn't seem like something so exotic that a watchmaker would not be able to service it. Any comments, opinions or owner experiences are appreciated.
Thanks,
Greg