How do I contact China Police?

I bought a Tractor and front end loader from YANCHENG FOREIGN TRADE CORP. LTD. I tried to check them out and they seemed to be a ligit company. I made a deposit and was promised that shipment would be within 30 days That was in Feb 2011 and this is June 2011. I would like to file a complaint againest YANCHENG FOREIGN TRADE CORP. LTD. Can someone help?