That was a very unfortunate incident indeed.
I hope your complaints are heard and corrective action taken.

I'm just guessing from the fact that you were flying back from PVG so I could be completely off base, but I wonder if subtle racism had something to do with it?
I have witnessed on countless occasions people of non-western-European descent being 'talked down to' in the US, especially if there is a strong accent.
(I have so far been fortunate enough not to have been a recipient of such treatment, at least not any that I noticed.)