Obtaining a business visa for China

Greetings, I would like to know the best way to obtain a business visa for my husband (Ukrainian citizen). We are in China now and he currently has a visa, but it will expire by the end of this month. A six month-visa without any limitations for entry, exit, and duration of stay would be ideal. Would you mind suggesting a reliable agent to help us do this in Hong Kong? You time and help is much appreciated.