How do you physically "extend" a visa? Do other countries have visas where you can print a new expiration date? You mentioned China, and I looked up images of a Chinese visa, there doesn't seem to be a place to put a new date, it has one field after 'Enter before', are you sure you got a new visa stamp with your extension of status?

i also reject the claim that there is no one inside any country that could verify the status of a foreigner

That's good since I haven't made such a claim!