I've been using Shenzhou for a over a year, and I've only ever used my USA Mastercard. And when I've been with friends who rented with them, they always used American credit cards too.

Perhaps when you went there was some kind of miscommunication? Or it wasn't the same company? At the very least you go a person who gave you incorrect information.
"Zuche" is in the name of every car rental place. The actual name of the company with the website "zuche.com" is 神州租车.

Can you let me know the address of the place you rented from? If they have a website please post it here too. I am referring to the nationwide chain that has 3 branches in Kunming. Those guys refused my overseas credit card (although they didn't try to swipe it, they just insisted on a Chinese credit card). Incidentally, they didn't care if one person had a license and another paid for the rental, but they did not accept my card. In the end, we decided not to rent from them, because the idea of having to use a Chinese credit card seems a bit far fetched.