okay, I think that
@N**
understands they have 3 choices
1 - do nothing pay the 4000 baht overstay fine at the airport when you leave (DON'T run amuck during the time you're on overstay)
2 - border bounce and get a new 30 day visa exempt entry
3 - go to the immigration office and get the extension denied 7 day stamp for 1900baht and then have one day of overstay on the day they fly out.
I think we're done ;)