Where can I get a 30-day Temporary Extension of Stay in Thailand?

I am at Chamchuri Square Immigration Office. I came to get a 30 day Temporary Extension of Stay. I was told that this service in not offered here at Chamchuri office and that I must go to the immigration office located in the Government Complex on Chaengwattana Road. I have US passport and entered via land crossing on Feb 22 at Tak Bai on border with Malaysia. I am very surprised because I read that the TES is offered here at Chamchuri office. I will go to the Government Complex tomorrow. Wish me luck.