do I have to go to Hong kong to get me extention,or can I get it be done in Chengdu?

Hi, you can try to extend it in Chengdu with the invitation letter. Following documents are required:
1. Valid Temporary Accommodation Registration Form issued by a local police station;
2. The host/hostess’s Household Register or Resident Identification Card and a letter in Chinese addressed to the Chengdu PSB. Or
you can provide a proof of hotel reservation, itinerary, and airline tickets etc. instead.

Hi, thank you very much for your help.

Kind regards

John