An extension of a visa does cancel the previous visa?

Hi, this is my personal situation:
- I entered the country with a F type (multiple entry) for one year, which stays of 30 days maximum. That was on September 10th.
- On October 9th, I requested the extension and was given 30 additional days up to November 9th. Then I was supposed to leave the country somewhere (HK, Macau...) and come back.
- I was thinking to go to Hong Kong in 2-3 weeks, just leave mainland and step back in, because with my multiple entry I do not need to do anything in Hong Kong, right?
- Now, I have just been told that I have to go to Australia for business next Monday. Coming back on October 26th.

So my question is: if I enter back mainland in October 27th, then I will get 30 more additional days to November 27th, or the limit keeps being the limit of my extension (November 9th)?

The administration of Kunshan does not know, or they are afraid of saying something or I don't know what.

I will appreciate any comment about it.

Xie xie