Changsha Education Examinations Institute is near Xuanwan Town in Hexi. You can take bus 12 from the railway station to the terminal (Xuanwan Town), and then find a motorcycle or taxi. They all know it's only a few dollars.
Tianxin District Admissions Office is located in Tianxin District Education Bureau, near He Long Gymnasium and Tianyang Lake. Many cars can arrive, depending on where you have been.
The yuhua district test center is also near the yuhua district government.