Seoul-->Shanghai-->New York (US Citizen)

I'm flying with China Eastern and am having a really hard time finding information for a customer service email. I'm an American citizen with a Visa working in Korea. I'll be traveling from Seoul to New York with a layover in Shanghai. I've read that I need to contact my airlines before flying, but what if I can't reach the appropriate person? Has anyone experienced this airline?

Thanks in advance!
Alyssa