is it possible to load food and other services to the upper deck in a380 and B747??. Now when I set the coordinates of the other food vehicle to the second deck , the vehicle does not arrive at the airplane .
Assuming you have the current version of GSX (including all the vehicles), the included CT8000 catering model can reach an height of 8.3 meters, which is correct according to real life specs, so it should be able to reach the A380 upper deck, provided (of course) you set the door's height correctly AND the 3rd party airplane you use has realistic dimensions.
Note that, if you set the door's height higher than 8.3 meters (even 8.31...), the vehicle won't be chosen.