Am I still eligible for the 72 hour free transit?

Hi, I am an Italian citizen, currently visiting New Zealand. On the way back to Europe (early November), I wanted to stop at Shanghai for a weekend. So, when I bought my ticket to NZ, I searched for return flights Auckland-Shanghai and Shanghai-Amsterdam. The stop is about 50 hours, but the flight Auckland to Shanghai is not direct. I am travelling with China Southern, and would get at Shanghai through a domestic transfer at Guangzhou. My friend living in China thinks that I might not be eligible for the 72 hours free transit, because Guangzhou would be considered the city where I arrive (and I need to arrive and depart from the same city). Did I actually make a mistake? I have tried to get in contact with the Chinese Embassy in NZ, but have not received an answer yet. If I do need a visa, where could I apply for one, since I am already in New Zealand? Thanks in advance for your answer.