you need to call gm customer service is what i think. they're paid by gm for diagnosis. actually i'd start with the service manager. techs and advisors don't always play by the rules so atleast give their boss the benefit of the doubt and start with him.
i pulled this off of the bulletin:
This special policy covers the condition described above for a period of 7 years or 200,000 miles (320,000 km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. The repairs will be made at no charge to the customer.
Important: This special policy only covers the above noted failure modes, which are identified by high fuel return flow.
For 2001-2002 vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after May 25, 2004, are covered by this special policy and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to May 25, 2004 must be submitted to the Service Contract provider.
For 2003 vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after October 10, 2006 are covered by this special policy and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to October 10, 2006 must be submitted to the Service Contract provider.