EMERGENCY Help with this mess!!ANOTHER VISA NEEDED!! IM TRAVELLING IN 2 WEEKS

Hello,
Im from greece,traveling to china for first time as turist.my embassy doesnt give a multiple visa which i need. my trip is guanhgzou-hong kong-guangshou-hanoi(vietnam)-shangai-tokyo-beijing.I booked already the tickets.Is there any way to get another visa in hanoi in 3 working days? or if im not going to hong kong can i get another visa from shangai?