But you can transfer.
1. You can buy a ticket at Wushan Cuiping Bus Station to go to Longxi Town, and then get off at Longxi. There will be buses or trucks, motorcycles and so on to Wuxi. (specifically ask the driver when you get on the bus, they all know), and the whole journey takes 5 hours.
2. Or you can take a passenger ship to Wuxi at Wu Shan Pier, which takes about 7 hours.
Or take a bus to Fengjie, where there is a bus to Wuxi.