I've posted this on another thread that I ran a year or so ago.
You can do just about all of the necessary crap at ANY immigration office. You definitely DO NOT need to keep returning to the same office you started with originally. It may take a minute or two to establish yourself but often times it is worth it. (There are exceptions of course, if your initiating a visa that ONLY the Bangkok office can issue)
There are at least two offices I've dealt with on the same retirement extension with absolutely no hassle or problems and the max time has been twenty minutes. It all depends on what office you use.
Yesterday an expat living in our condo was over the moon with regards to me telling him to go to the Samut Prakan office for his 90 day visit. His quoted comment: "WOW that was easy, if I hadn't told the taxi driver to wait I would have stayed and chatted with them for a few minutes, very pleasant staff."
Yep, the taxi driver waits while you go in and get your stamps sorted... takes at most five minutes. Another comment: "If I lived next to the immigartion office in town I would take a taxi out here, its that good!"
Another great immigration office is Pong nam ron (sp?) near the Cambodian border on highway 317 out of Chantaburi. Great folks and will try and keep you hanging out to keep the conversation going. The lady in charge of the office is the one that clued me into the fact that ALL imigration offices can do anything you need.
If your are about to redo your visa it may help to go back to the originating office and get a copy of your 'file' (no charge) but is totally unnecessary. In the two offices I've mentioned I've never spent more than 10 minutes waiting in line.
Typically in the Samut Prakan office, if there are folks from the area's companies with lots of passports getting processed, you walk in and almost immediately (or when the opportunity arises) one of the women will push aside the corporate stuff and wave you into the process and idicate a seat for you to take. You get your stuff done and she returns to handling the coporate pile. Very nice and sociable and no one gets a hair across their ass. Totally civil.
E. G.
EDIT: If your on a 90 day reporting period it helps to take a couple of forms with you so that you can have it filled out when you get there, no hassle trying to find a pen that functions etc.