Wow. I had mine updated a few months ago. No voucher needed:
http://www.gm-trucks.com/forums/topic/192290-android-auto/?do=findComment&comment=1870409
I hope the next gen trucks will be capable of OTA HMI updates
Do you have led bulbs in your garage door opener? I read something that stated led bulbs emit a frequency that can cause trouble. I didn't believe it myself until I changed back to CFL and range went back to normal.