dear dp,
rr can't write an invoice for you. He has to go back to the vendor and fill the form I mentioned above. Then when he/she leaves the country he has to show the phone and his passport (that has a non EU address in it) along with the same day BP to the customs officer and get a certification of export. This cert he then carries back to the vendor to get the refund.
If he doesn't have the required passport, you need to go to the german consulate in china and get a certification from them by showing your docs.
http://www.peking.diplo.de/Vertretun...st__seite.html
Oh, BTW, you have to do this within 90days of the original purchase.
RR writing an invoice doesn't work, unless he has a USt number for his business.