The best way to prevent the frozen door locks is preventive maintenance: Pull the door handle out (like you're opening up the door) and spray inside the exposed holes with a good quality silicone lubricant spray. I've had good luck with this method, some folks use a dilute glycol or antifreeze that they squirt in there.

I spray inside my door handle mechanism once every couple weeks during the winter, and since I've been doing that I've never had an issue.

It's a bunch of crap for a $55K vehicle, but that's the way it goes I guess.