GMC 2012 Sierra Denali Owner's Manual page 454

However, we recognize that despite
the good intentions of all parties
involved, sometimes a
misunderstanding may occur.
If you have a problem that has not
been satisfactorily handled through
the normal means, we suggest the
following steps:
Explain your case to your dealer
service agent, service manager,
dealer sales agent, or sales
manager, depending on your case.
Make sure that they have all
necessary information. They are
interested in your continual
satisfaction.
If you are not satisfied, please
contact the general manager or your
dealership owner to ask for their
help. If they are not able to resolve
your case, ask them to contact the
right people at General Motors for
support, if needed.
If your case is not resolved in a
reasonable amount of time by your
dealer, please call the General
Motors Customer Assistance
Center (CAC) and provide the
following information:
Name
Address
Phone number
Model year
Brand
Vehicle Identification
Number (VIN)
Mileage
Delivery date
Description of the problem
Dealership name
Dealership address
See
for more
information.
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:
GMC Customer Assistance Center
P.O. Box 33172
Detroit, MI 48232-5172
www.GMC.com
1-800-GMC-8782 (1-800-462-8782)
1-800-462-8583 (For Text
Telephone Devices (TTYs))
Roadside Assistance:
1-888-881-3302
or