@Taketo *********
Here's how it works
IF you BOUGHT a tourist visa from a thai consulate before you came here and were stamped in for 60 days when you arrived you go to the main immigration office at Chaengwattana gov't complex building B, counter J
BUT
IF you showed up here without any visa in your passport and were stamped in FREE on what's called a visa exempt entry you go to Muang Thong Thani Immigration office out by Impact Arena in the police compound there and you want counter K