How to avoid having the wandering jetways save bug ruin your game.
Fixing the Problem
If, once after you've saved the game to avoid another CTD erasing some progress, you've failed to notice all your jetways are now moving of their own free will (yes, even the ones called 1A, 2A, etc), chances are good you've borked the AI's ability to play the game on its own. Here's a relatively simple fix to restore that playability so you can finish upgrading the airport.
What you'll want to do is use the fuel tanker below on the errant gates, like the one shown ahead of it sticking through the gate tower housing:
You need to drive under and snag the leading edge of the gate with the leading edge of the tank trailer, and keep dragging the jetway ever so slowly back around the gate housing to its proper position (where you'd normally "steer" and park them to in manual control), or close to it.
If the AI is already controlling one of the borked jetways, usually it drags it into the nose of the plane being serviced and gets stuck. A few good whacks from the tug should dislodge it.