Rent Car with driver in Gansu

Hi, im planning a trip through Gansu with my parents next weeks. We're looking for a driver (or a driver company) to move from place to place.
We haven't a planned itinerary yet, but anyway we're gonna visit all the main sites (from Lanzhou, Zhangye, Xiahe, Jiayuguan, Dunhuang,...).
Do you have any recommendations?
Thanks for any help!
Andrea