Invitation letter is the main issue.. super confusing

We live in Dubai. And are Pakistani Nationals.
Won a competition through VoxCinemas and they are sending us to shanghai for 4 days (arranging for round trip tickets, hotel stay, city tour etc)
Now we asked them for the invitation letter as well, and they said they'll get us an invitation letter from the hotel.
However the chinese embassy here says that the invitation letter should be from the government body of china.

What to do now :S super confused
also how many days does it take for the letter to come? aur flying dates are coming near