My Overstay Horror Story

I am a U. S. Citizen with a Business visa for Mainland China. I went to Hong Kong last October to renew my multiple-entry requirement. When I returned to Mainland China a small piece of paper was placed in my Passport which said my visa was good for 90 days. This was placed in my Passport by the Hong Kong Immigration officials. I totally misunderstood what it was for and thought it ment I got an extention maximum stay for my Mainland China entry permit. I was wrong. When I left China again last February I was told by the Chinese Immigration official that I had overstayed and had to pay a fine of 8000 RMB. To shorten the story, the officials eventually waived the fine, and let me enter and exit Hong Kong. But they did not give me any documents stating that my fine had been waived. When I left for USA last April, the immigration office at the Beijing Airport spotted the big gap of time in my Entry and Exit date stamps. Because I did not pay the fine in February and had no documentation I still was obligated to pay for this overstay. Repeat. The small notice placed in your Passport regarding your length of stay is only for Hong Kong not for Mainland China.