Try using CNX Seed https://www.cnxseed.com/cmxseedforumn/index.php#c11

It's in Thai but even with the crappy google translator, you can work out enough to find some details. Message them in Line/Wechat, they can understand english.

I think Chiang Mai Locator gets some kickbacks as the some of the shops they say is no good, has been very good.