Originally Posted by
crocodilexp
First, talk to the building owner if you haven't already. Most often, staff in Thailand cannot make any decisions on their own or do anything out the ordinary without the owner's approval. They're also greng jai and reluctant to pass on negative news/requests to the owner, unless forced.
As others mentioned, withholding the rent is the only real leverage you have, and it works especially well if the place is expensive and has low-ish occupancy. Do warn the owner beforehand that you will do it if your problem is not fixed (either by plugging the leak or moving you to a new unit), and pay after it has been fixed. One thing that's certain is that you aren't getting any money you already paid back (possibly including your deposit, especially if there's a conflict).
If your Thai wife or her family knows a cop, preferably senior, you could ask him for a favor to stop by and talk to the staff. This is not a criminal matter, but cops in Thailand often act as dispute mediators, and Thais do listen to casual requests from them, since it shows that you may have some leverage in case of conflict. Of course, if it comes to this, be prepared to pay the cop, and agree to an eventual compromise he may devise (e.g. splitting the portion of the repair cost). Cops tend to have more authority than lawyers around here.
I wouldn't stand outside with the sign. That might work, but could also backfire quite badly. If you make the owner or staff lose face in public, even if they fix your problem promptly with a Thai smile, they'll hold a grudge and you'll need to watch your back as long as you stay at that place.