Please help me get new fridge cooling better...

He shouldn't have to do anything. Airstream is one of the few manufacturers to use the environmental chamber that Dometic has- they put the rigs in very high temperatures to see how the installation is. While they often look like bad installs, for some reason they work.
I would, however, check the venting for obstruction, and make sure light goes out when you close the door. Otherwise I think it's service time- those temps are nowhere near good enough.