Chinese overstay

My wife is From China and we currently came to Pattaya.
10 days ago we came to the immigration office Chonbiru and they told us that for now Chinese citizens do not need to apply for an extended stay.
They said only overstay and there will be no fee.

Today we are back at Chonbiru to extend my stay as an American. We asked them about the Chinese stay and one worker told us at the airport when you leave there will be a fine....
but then another worker said No there will be no issue or pay.

We feel we don’t know who to believe now.
Please help us out