@Béatrice **************
Just had a friend who tried to get his extension based on banked money. Last year he met the criteria to apply for the extension BUT rather than keeping the 800K baht in the account for 3 months (3 months date to date) he thought he needed to keep the funds in for only 90 days and when he went for his new extension they noticed he was short the 3 month seasoning by 2 days 😮 and he was denied an extension.
Thankfully he'd applied about a month early and he was able to just walk away from the office (as in withdraw his application for extension) AND buy a ticket out of the country.
Because he didn't actually apply for the extension (he was just told he'd be denied) he wasn't actually on any overstay "yet", so got out without a problem. He will get a new O-A visa and come back at the beginning of next year.