A PVC balcony door that separates the room from the outdoors (which is currently −20 Celsius) is about six feet tall and about two feet wide. It is attached with two hinges - the upper one

and the lower one

placed at the door corners.
The horizontal (short) sides of the door adhere to the frame perfectly and so do the vertical (long) sides near the corners.
The vertical (longer) side of the door also has two pairs of these metal parts that are meant to push the door onto the frame. They are located on the same side as the hinges. They are not latches or anything else with moving parts - just two solid pieces of metal with carefully designed shape:



and those parts are firmly attached with screws (and everything is tight and looks sound) and show nothing that could possibly be adjusted.
The problem is that everywhere except the corners the vertical (long) side of the door bends to the inside of the room and doesn't adhere to the frame and so the rubber gasket is not pressed onto the frame and lets cold air in. I guess something should be done to those two-component parts that force the door onto the frame, but have no idea what that should be.
How do I make the door with such hinging system adhere to the frame everywhere and not let air from the outside in?