Transit Guangzhou but have to stay slightly longer than 72 hours

Hi there. We hold NZ passport and are going through Guangzhou to Kazakhstan. Arriving to Guangzhou on the 02/07/2018 at 6 am and then flying out to Almaty on the 5th of July at 12.40 so it's about 4 hrs more. What shall we do? Apply for a visa or get out from the airport at around 12 on arrival? Thanks.