Ask your hotel to print a copy of the tm 30, if you have to go to immigration for an extension. Stuff goes wrong and having the print out from the hotel helps smooth things over.
Oh and the first person this morning saw my phuket extension and told me to go back to phuket. I showed them my bkk tm 30 and had to insist that I am to do it here at IT square.
Went back 20 min before 4. They asked do I have priority. Showed my expiring today visa and they gave me a separate que card. Didn't ask for flights again, but they did verbally ask this morning when I was flying out. Got an underconsideration stamp. Said if I leave the country before the return date I'm fine.
Unfortunately. Went to phuket as well weeks ago to do this and was told to go away. I'm going in and won't leave until they put a stamp in my passport.