See also:

Customer Assistance Offices (U.S. and Canada)
GMC encourages customers to call the toll-free number for assistance. However, if a customer wishes to write or e-mail GMC, the letter should be addressed to: United States GMC Customer Assistance ...

MP3 and WMA Supported Files
Format The radio can play.mp3 or .wma files that were recorded onto a CD-R or CD-RW disc. Compressed Audio or Mixed Mode Discs The radio plays discs that contain both uncompressed CD audio and MP3/ ...

Unable to Connect to OnStar Message
If there is limited cellular coverage or the cellular network has reached maximum capacity, this message may come on. Push to try the call again or try again after driving a few miles into another ce ...