Some great advice here
This was my experience a few months ago transiting on AC, also through PVG for 3 days
China 72 hour transit visa. Need to inform Air Canada?
The great advice already mentioned which I would repeat:
1. Have a hard copy of all your documents handy
2. Definitely bring a printout from TIMATIC. This helped us immensely when they incorrectly ran their search showing china as the destination
3. Politely but firmly hold your position
The most annoying thing about the program was on arrival. Processing was extremely slow and also involved our names and hotel reservations being written by hand into a book