Need a tourist Visa to Shanghai - China - Iranian Citizen

Hi

AM an Iranian citizen and resident in Kuwait, I went to Chinese Embassy in Kuwait and they told me I should have an official invitation letter issued by the ministry of foreigner affairs in Shanghai and a letter from the Chinese company, the FAO letter will need long time something between 4 to 5 weeks. in this case can I courrier my passport to Iran through DHL and apply for a tourist L through travel agency?? and what is the normal cost and processing time??