Ok so thanks Tod for solving this mystery via pm. They recieved the letter from the Chinese embassy to say they couldn't travel and was meant to be taken to Phuket immigration to request a 30 day extension but they thought the letter was an extension. Overstay was from before the amnesty started. So it's all legit and above board.
ok... my accountant told me that and paid 30k to instead get an extension and not have to do any visa runs at all, now just have to show up at immigration office in phuket every 3 month.