ralphpam,
While not a fix for the t-stat, I never use mine as a t-stat. I use mine as an on/off switch. In fact, I have a 3-speed, rain sensor unit in my commode room and have a wall switch for it as it seemed more practical.
In my next unit, if I am unable to get a remote controllable fan, I may just ask for a wall switch instead of a t-stat.
Calling Fantastic Vent directly should yield decent results. Let us know.
Jim