VOA to China

Hi, need a very accurate information here. I plan to visit HK on 22 - 25 jan, and planning to visit guangzhou after that. My question is, can I apply for a VOA in Shenzen? and how many days available for my visit? because im planning to go there on 25 and go back home on 4th february which is 11 days. And also, I have visited China twice last year, if it can make a difference.
anyone can give me an advice? thankyou so much