T108 train Shenzhen to Beijing west

Please inform how to find train ticketing offices in Nanshan district, Shenzhen. We have 2 address, one office is in Nanshan Av. (which part, which number?) and another is in Dongbin road (which part, which number?). No one is replying on the telephone. We have been trying to find them, no success. Thank you in advance for your early reply.