Okay, the O/P already got the :loop closed" from their under consideration stamp and are on the actual extension. :)
That means seeing as it was a tourist visa they entered on and as a rule tourists TOUR, they can apply for a new 60 day extension where ever they happen to be staying IN thailand.
SO
@De**
, IF you're staying in Isaan (and the place they stay at files a TM30 on them) you shouldn't have any problem applying for the 60 day extension there.
BUT
Remember, like
@Ja***
said, IF you get the under consideration stamp up there, you're stuck and need to stay up there until you get the "loop closed". :O