Ok. Tomorrow (Wednesday 17th) immigration offices will be open. Many of the major ones like Bangkok, Chiang Mai, Jomtien, Phuket, etc will be off the wall charts busy after a 5 day closure. ๐๐ ๐ฒ๐จ๐ฎ ๐๐๐ง ๐ฉ๐จ๐ฌ๐ฌ๐ข๐๐ฅ๐ฒ ๐๐ฏ๐จ๐ข๐ ๐ ๐จ๐ข๐ง๐ ๐ญ๐จ๐ฆ๐จ๐ซ๐ซ๐จ๐ฐ ๐ญ๐ก๐๐ง ๐ฉ๐ฅ๐๐๐ฌ๐ ๐๐จ ๐ฌ๐จ. Theyโre open on Thursday and Friday too and will probably be a lot less busy.
If you have had a stamp that has expired since the 12th then definitely go tomorrow (early in the morning). You can get an extension as normal but you will get an overstay stamp but not a fine as the offices were closed. The extension will be dated from the day it was due.
If the wait times are astronomical then please donโt blame the staff. They will be working as best they can but it will certainly be hard to cope with the sheer numbers that turn up.