what is the fastest way to go to guangzhou from Shenzhen.

From shenzhen, what is the fastest way to go to guangzhou for 7 adults and 2 children. how much is it to hire a van for one full day and from whom can i hire this van? If train, where do i take the train, as i cannot speak any chinese, i think it is better to hire a van. what is your opinion?
Thank you