http://www.flyertalk.com/forum/thail...g-service.html

AFAIK, there is no way to purchase SRT tickets on-line since they cancelled this service ! 14 Jan. 2013. I do not believe there are any other sites, so finding a local agent for advanced tickets may be the only option? I do not know of any local agents but it should be easy to find some with a search?

SRT sells tickets up to 60 days in advance of travel, and premium services (1st/2nd class sleepers) between popular destinations (Bangkok-Chiang Mai) do sell out quite quickly, especially for weekends and holidays.

I have seen travel agents purchasing hundreds of tickets at Hua Lumphong, for Songkhran travel, so they do get stock-piled.

What days/dates/routes were you looking to travel? Do you have a local contact? Post back if you are unable to find an agent.