This:
http://www.heatshieldstore.com/
It will help even if Chevy gets a fix. When ever parked outside use one of these. Stopped at store etc use it. It will help if not solve the issue. I use this brand on all five of my rides. I have and 83 grand prix and 90 sub that sit out and dash is perfect.
Oh and the car is a lot cooler so less work on the air conditioner, no hot seats etc...