China Train Tickets

I want to book a ticket from Shanghai to Chengdu in advance but I am currently travelling in China and do not have a permanent address. If I book a ticket from you, would I be able to pick this up at the station? Do you provide a reference number to pick up the tickets? I will only be arriving to Shanghai a few days before I want to get the train so I need to be sure that I will definitely be able to get them. I would be grateful for any more information you can give me.