validity of passport

My son has Turkmenistan passport without expired date. Embassy rejected to give him visa to China without letter from Turkmenistan embassy about validity of his passport. Can this letter be fax directly to China Embassy in Kuala-Lumpur or i can get it by e-mail to my address and later submit with others documents. Please write me the best possible solution, becouse Turkmenistan Embassy in China not willing to sent this letter by post. thank you very much