Child born in China. Received Singapore passport of his own. How to get an exit permit.

My boy is now 8 mths old. He is born in a hospital in Zhongshan City, Guangdong province. I am a Singaporean and my wife is from Qingyuan City. My boy has just received his Singapore Passport. I went to Zhongshan City Exit-Entry Administrative Bureau of Public Security Bureau to apply for my boy's exit and at the same time apply for his visa to stay in China with his mother. Zhongshan Exit-Entry Administrative Bureau of Public Security Bureau told me that my boy can only apply at his mother's native birth place. In order to confirm before my family travel to Qingyuan City Exit-Entry Administrative Bureau of Public Security Bureau. I asked my wife to call Qingyuan Exit-Entry Administrative Bureau of Public Security Bureau just to make sure we do not missed bringing any document. However Qingyuan Exit-Entry Administrative Bureau of Public Security Bureau told my wife, that since my boy is born and residing in Zhongshan, we can apply in Zhongshan Exit-Entry Administrative Bureau of Public Security Bureau. Now, that is contradicting what Zhongshan Exit-Entry Administrative Bureau of Public Security Bureau said.

Kindly advise who is right, Zhongshan or Qingyuan Exit-Entry Administrative Bureau of Public Security Bureau? Thank you.